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3<br />

! General information! ! ! ! 4<br />

!<br />

! Programme!! ! ! ! ! 5<br />

!<br />

! List of Participants! ! ! ! 10<br />

! Abstract of contributions! ! ! 14<br />

!<br />

Insights from Solar System planets! ! 14<br />

Terrestrial planets! ! ! ! 22<br />

Super-Earths and hot Neptunes! ! 31<br />

Hot Jupiters: observations! ! ! 38<br />

Hot Jupiters: models! ! ! ! 51<br />

Young giant planets and brown dwarfs! 57

Presentation<br />

Venue<br />

Davos is a winter resort in the East of Switzerland, at 1560 m one of the<br />

highest town in the Alps. Its showpiece is the <strong>Conference</strong> Centre, which<br />

hosts the World Economic Forum every year.<br />

<strong>Exoclimes</strong><br />

Previous <strong>Exoclimes</strong> conferences have taken place in Exeter, UK, in<br />

September 2010, and Aspen, CO in January 2012. The objective of these<br />

conferences is to bring together specialists of the Earth, Solar System<br />

planets and exoplanets to discuss the new field of comparative<br />

planetology outside the Solar System.<br />

Contact<br />

In case of need during the conference, contact the organisers at<br />

exoclimes@gmail.com or call +41 77 418 58 12.<br />

Emergency numbers in Switzerland are<br />

117 for police,<br />

118 for fire and<br />

144 for ambulance.<br />


<strong>Exoclimes</strong> III<br />

Exploring the Diversity of Planetary Atmospheres<br />

Davos 9-14 February 2014<br />

Monday 10th<br />

Programme<br />

8:00! Desk opens<br />

8:50! Welcome address<br />

Session: Earth-like atmospheres<br />

9:00! Exotic atmospheres (review): Pierrehumbert<br />

9:40! A new perspective on the inner edge of the habitable zone: Leconte<br />

10:05! Break<br />

10:30! Paleo-climates (review): Abbot<br />

11:10! Exoplanetary extreme space weather: Cohen<br />

11:35! Terrestrial planet atmospheres in the aftermath of giant impacts: Lupu<br />

12:00 ! Lunch break<br />

Session: Interiors<br />

17:00! Interior-atmosphere interactions (review): Elkins-Tanton<br />

17:40! Earth’s interior dynamics (review): Tackley<br />

18:05! Break<br />

18:20! Magneto-hydro-dynamics: T. Rogers<br />

19:00! Evening break<br />


Programme<br />

Tuesday 11th<br />

Session: Exoplanet observations<br />

8:30! Exoplanet transit observations (review): Desert<br />

9:10! Characterising exoplanet atmospheres with HST/WFC3: Mandell<br />

9:35! Revealing distant worlds with ground-based spectroscopy: Stevenson<br />

10:00! Break<br />

10:30! Exoplanet eclipse/phase observations (review): Knutson<br />

11:10! Observation highlights –<br />

! Ground-based detection of water in hot Jupiters: Birkby<br />

! Probing the atmosphere of non-transiting planets: Brogi<br />

! 2D mapping of the eccentric planet HAT-P-2b: de Wit<br />

! Mapping clouds in exoplanet atmospheres: Demory<br />

! Measuring the reflection signal of HD 189733b: Evans<br />

! Atmosphere of exo-Neptune HAT-P-11b: Fraine!<br />

! Transmission spectroscopy of super-Earth GJ1214b: Kreidberg<br />

! HST/STIS transmission spectral survey: Nikolov<br />

12:00 ! Lunch break<br />

14:00! Workshop on transit observations: Sing<br />

Session: Clouds and hazes<br />

17:00! Photochemistry (review): Moses<br />

17:40! Overcoming remote sensing challenges for cloudy atmospheres: Barstow<br />

18:05! Break<br />

18:20! Recent advances in exoplanet climate simulations: Showman<br />

19:00! Evening break<br />


Wednesday 12th<br />

Session: Circulation models<br />

8:30! Exoplanet circulation models (review): Menou<br />

9:10! Non-hydrostatic, deep-atmosphere hot Jupiter climate models : Mayne<br />

9:35! Water loss from N2/CO2-atmosphere terrestrial planets: Wordsworth<br />

Programme<br />

10:00! Break<br />

Session: Evaporation and energy<br />

10:30! Global energy budgets for terrestrial and gas giant exoplanets: Read<br />

11:10! Models of exoplanet evaporation: Owen<br />

11:35! Enshrouded close-in exoplanets : Haswell<br />

12:00 ! Lunch break<br />

Session: Outer Solar System<br />

17:00! Titan’s atmosphere (review): Mitchell<br />

17:40! Measurement of the atmospheres of Europa, Ganymede and Callisto: Wurz<br />

18:05! Break<br />

18:20! Jupiter’s atmosphere (review): Kaspi<br />

19:00! Evening break<br />


Programme<br />

Thursday 13th<br />

Session: Brown dwarfs and directly-imaged planets<br />

8:30! Brown dwarf observations (review): Apai<br />

9:10! Results from the “Weather on other worlds” Spitzer campaign : Metchev<br />

9:35! Doppler imaging of a nearby cloudy brown dwarf: Crossfield<br />

10:00! Break<br />

10:30! Model brown dwarf spectra (review): Barman<br />

11:10! Connecting low-gravity brown dwarfs and directly-imaged planets: Liu<br />

11:35! The mid-infrared properties of directly-imaged planets: Skemer<br />

12:00 ! Lunch break<br />

Session: Synthetic spectra<br />

17:00! Model exoplanet spectra (review): Fortney<br />

17:40! Simulated transit spectra of Earth and Jupiter: Irwin<br />

18:05! Break<br />

18:20! Poster session<br />

19:00! Evening break<br />


Friday 14th<br />

Session: Atmospheric retrieval<br />

8:30! Chemical characterisation of super-Earths: Madhusudhan<br />

8:55! A comparison of exoplanet retrieval techniques: Line<br />

9:20! The atmospheres of GJ1214b and GJ436b: Benneke<br />

9:40 ! Discussion<br />

Programme<br />

10:00! Break<br />

Session: Theory<br />

10:30! Helium-dominated atmosphere on Neptune-size GJ436b: R. Hu<br />

10:55! Ionisation regimes structuring planetary atmospheres: Helling<br />

11:20! Ocean transport in the climate of exoplanets around M-dwarf stars:<br />

! Y. Hu<br />

11:40 ! Atmospheric super-rotation: Lewis<br />

12:00 ! Lunch break<br />

Session: Earth-like exoplanets<br />

17:00! Climate dynamics (review): Schneider<br />

17:40! Climate and photochemistry of potentially habitable exoplanets: Tian<br />

18:05! Break<br />

18:20! The prospects for characterizing the atmospheres of rocky exoplanets:<br />

! Charbonneau<br />

19:00! Evening break<br />


Participants<br />


Dorian! Abbot! University of Chicago<br />

Miquela! Abbot! University of Chicago<br />

Nadine! Afram! Kiepeneheuer Inst. für Sonnenphysik! p. 51<br />

Suzanne! Aigrain! University of Oxford<br />

Yann! Alibert! University of Bern! p. 22<br />

David! Amundsen! University of Exeter! p. 52<br />

Daniel! Angerhausen! Rensselaer Polytechnic Institute! p. 38<br />

Daniel! Apai! University of Arizona<br />

Jeremy! Bailey! University of New South Wales! p. 39<br />

Travis! Barman! University of Arizona<br />

Joanna! Barstow! University of Oxford! p. 14<br />

Jean-Loup! Baudino! LESIA, Observatoire de Paris! p. 57<br />

Jacob! Bean! University of Chicago<br />

Thomas! Beatty! Ohio State University! p. 58<br />

Björn! Benneke! California Institute of Technology! p. 31<br />

Andrei! Berdyugin! FINCA, University of Turku! p. 39<br />

Svetlana! Berdyugina! Kiepeneheuer Inst. für Sonnenphysik! p. 22<br />

Zachory! Berta-Thompson! Massachusetts Inst. of Technology! p. 32<br />

Jayne! Birkby! Leiden Observatory! p. 39<br />

Jasmina! Blecic! University of Central Florida! p. 52<br />

Kimberly! Bott! University of New South Wales! p. 52<br />

Vincent! Bourrier! Institut d’Astrophysique de Paris! p. 40<br />

Matteo! Brogi! Leiden Observatory! p. 40<br />

Carolyn! Brown! University of Southern Queensland<br />

Matthew! Browning! University of Exeter<br />

Ben! Burningham! University of Hertfordshire! p. 58<br />

Ludmila! Carone! CmPA, KU Leuven! p. 23<br />

David! Charbonneau! Harvard University! p. 23<br />

Ofer! Cohen! Harvard-Smithsonian CfA! p. 24<br />

Vincent! Coudé du Foresto! Paris Observatory / Bern University<br />

Nicolas! Cowan! Northwestern University! p. 32<br />

Ian! Crossfield! Max Plank Institute for Astrophysics! p. 58<br />

Nicolas! Crouzet! Dunlap Institute, University of Toronto! p. 41<br />

Patricio! Cubillos! University of Central Florida! p. 41<br />

Mario! Damasso! INAF-Astrophysical Obs. of Torino! p. 32<br />

Remco! de Kok! SRON / Leiden Observatory! p. 41<br />

Julien! de Wit! Massachusetts Institute of Technology! p. 42<br />

Laetitia! Delrez! University of Liège<br />

Brice-Olivier! Demory! Massachusetts Institute of Technology! p. 42<br />

Jean-Michel! Desert! University of Colorado<br />

Hannah! Diamond-Lowe! University of Chicago<br />


Ian! Dobbs-Dixon! NYU Abu Dhabi! p. 53<br />

Caroline! Dorn! University of Bern<br />

Diana! Dragomir! University of California/LCOGT! p. 33<br />

Benjamin! Drummond! University of Exeter<br />

Siegfried! Eggl! IMCCE, Observatoire de Paris! p. 24<br />

Lindy! Elkins-Tanton! DTM, Carnegie Institution<br />

Justin! Erwin! University of Arizona! p. 53<br />

Lisa! Esteves! University of Toronto! p. 43<br />

Tom! Evans! University of Oxford! p. 43<br />

Jacqueline! Faherty! Carnegie Institution of Washington, DTM<br />

Sean! Faulk! University of California, Los Angeles! p. 14<br />

Dora! Fohring! Durham University! p. 43<br />

Doris! Folini! ETH Zürich<br />

Jonathan! Fortney! University of California-Santa Cruz<br />

Jonathan! Fraine! University of Maryland! p. 33<br />

Richard! Freedman! SETI Institute<br />

Sebastien! Fromang! CEA Saclay<br />

Antonio! GarcÌa Muñoz! RSSD, European Space Agency! p. 19<br />

Neale! Gibson! European Southern Observatory! p. 43<br />

Daniel! Gisler! Kiepeneheuer Institut für Sonnenphysik! p. 15<br />

John Lee! Grenfell! German Aerospace Centre (DLR)! p. 24<br />

Simon! Grimm! University of Zurich! p. 53<br />

Sandrine! Guerlet! Laboratoire de Métrologie Dynamique! p. 15<br />

Aimee! Hall! University of Cambridge! p. 34<br />

Joseph! Harrington! University of Central Florida! p. 44<br />

Carole! Haswell! The Open University! p. 44<br />

Christiane! Helling! University of St Andrews! p. 59<br />

Kevin! Heng! University of Bern! p. 54<br />

Klemens! Hocke! University of Bern<br />

Jens! Hoeijmakers! Leiden Observatory<br />

Derek! Homeier! CRAL/ENS-Lyon! p. 59<br />

Yasunori! Hori! National Astronomical Observatory Japan! p. 34<br />

Andrew! Howard! University of Hawaii<br />

Renyu! Hu! California Institute of Technology! p. 34<br />

Yongyun! Hu! Peking University! p. 25<br />

Nicolas! Iro! Klimacampus - University of Hamburg! p. 54<br />

Patrick! Irwin! Oxford University! p.16<br />

Kate! Isaak! ESTEC, European Space Agency<br />

Joshua! Kammer! California Institute of Technology! p. 35<br />

Yohai! Kaspi! Weizmann Institute of Science<br />

Tiffany! Kataria! University of Arizona! p. 25<br />

Hajime! Kawahara! University of Tokyo! p. 45<br />

Lucyna! Kedziora-Chudczer University of New South Wales! p.16<br />

Participants<br />


Participants<br />

Sara! Khalafinejad! Hamburg Observatory<br />

Flavien! Kiefer! IAP! p. 60<br />

Cevahir! Kilic! University of Bern! p. 26<br />

Daniel! Kitzmann! Technical University Berlin! p. 55<br />

Heather! Knutson! California Institute of Technology<br />

Daniel! Koll! University of Chicago! p. 36<br />

Thaddeus! Komacek! University of Arizona! p. 55<br />

Tommi! Koskinen! University of Arizona! p. 56<br />

Nadia! Kostogryz! Kiepeneheuer Inst. für Sonnenphysik p.16<br />

Laura! Kreidberg! University of Chicago! p. 36<br />

Oleksii! Kuzmychov! Kiepeneheuer Inst. für Sonnenphysik!p. 60<br />

Panayotis! Lavvas! CNRS (France)<br />

Alain! Lecavelier! Institut d’Astrophysique deParis! p. 56<br />

Jeremy! Leconte! CITA/LMD! p. 26<br />

Jae-Min! Lee! University of Zurich! p. 60<br />

Emmanuel! Lellouch! Observatoire de Paris<br />

Stephen! Lewis! The Open University! p. 17<br />

Michael! Line! University of California-SC! p. 61<br />

Jeffrey! Linsky! University of Colorado<br />

Michael! Liu! University of Hawaii! p. 61<br />

Joe! Llama! University of St Andrews! p. 45<br />

Eric! Lopez! UC Santa Cruz! p. 36<br />

Roxana! Lupu! SETI Institute! p. 27<br />

Nikku! Madhusudhan! University of Cambridge! p. 37<br />

Jared! Males! University of Arizona! p. 61<br />

Luigi! Mancini! Max Planck Insitute for Astronomy<br />

Avi! Mandell! NASA Goddard! p. 46<br />

Nadejda! Marounina! Laboratoire de Planetologie, Nantes! p. 17<br />

Stephen! Marsden! University of Southern Queensland! p. 27<br />

Nathan! Mayne! University of Exeter! p. 56<br />

Victoria! Meadows! University of Washington<br />

Joao! Mendonca! University of Bern! p.18<br />

Kristen! Menou! Columbia University<br />

Stephen! Messenger! Massachusetts Inst.of T echnology<br />

Stanimir! Metchev! University of Western Ontario! p. 62<br />

Alison! Mitchell! University of Californa LA<br />

Jonathan! Mitchell! University of Californa LA<br />

Pilar! Montanes-Rodriguez Inst. de Astrofisica de Canarias! p. 18<br />

Caroline! Morley! University of California-Santa Cruz! p. 62<br />

Katie! Morzinski! University of Arizona! p. 62<br />

Julie! Moses! Space Science Institute<br />

Norio! Narita! National Astronomical Obs. Japan! p. 37<br />

Nikolay! Nikolov! University of Exeter! p. 46<br />

Lisa! Nortmann! Institut für Astrophysik Göttingen! p. 47<br />

Joseph! O'Rourke! California Institute of Technology! p. 47<br />


James! Owen! CITA! p. 48<br />

Hannu! Parviainen! University of Oxford! p. 48<br />

Enric! Palle! Instituto de Astrofisica de Canarias! p. 48<br />

Raymond! Pierrehumbert!University of Chicago<br />

Frédéric! Pont! University of Exeter<br />

Max! Popp! Max Planck Institute for Meteorology! p. 28<br />

Ramses! Ramirez! Pennsylvania State University<br />

Peter! Read! University of Oxford! p. 19<br />

Tyler! Robinson! NASA Ames Research Center! p. 20<br />

Leslie! Rogers! California Institute of Technology! p. 37<br />

Tamara! Rogers! University of Arizona<br />

Sarah! Rugheimer! Harvard University<br />

Josiane! Salameh! Max Planck Institute for Meteorology! p. 28<br />

Tapio! Schneider! ETH Zürich<br />

Henriette! Schwarz! Leiden Observatory! p. 49<br />

Aomawa! Shields! University of Washington! p. 29<br />

Adam! Showman! University of Arizona<br />

Avi! Shporer! Caltech/JPL! p. 49<br />

David! Sing! University of Exeter<br />

Andrew! Skemer! University of Arizona! p. 63<br />

Kevin! Stevenson! University of Chicago! p. 50<br />

Paul! Tackley! ETH Zürich<br />

Zhihong! Tan! Caltech/JPL! p. 29<br />

Feng! Tian! Peking University! p. 29<br />

Kamen! Todorov! ETH Zürich! p. 50<br />

Pascal! Tremblin! University of Exeter<br />

Vincent! Van Eylen! Aarhus University! p. 50<br />

Tamas Norbert ! Varga! Eötvös Lorand University<br />

Giovanni! Vladilo! INAF-Astrophysical Obs. of Torino<br />

Hannah! Wakeford! University of Exeter! p. 51<br />

Yuwei! Wang! Peking University<br />

Paul Anthony! Wilson! University of Exeter! p. 63<br />

Peter! Woitke! University of St Andrews! p. 57<br />

Robin! Wordsworth! University of Chicago! p. 30<br />

Peter! Wurz! University of Bern! p. 20<br />

Aurélien! Wyttenbach! University of Geneva! p. 38<br />

Fei! Yan! ESO! p. 21<br />

Jun! Yang! University of Chicago! p. 30<br />

Angela! Zalucha! SETI Institute! p. 21<br />

Robert! Zellem! University of Arizona! p. 51<br />

Andras! Zsom! Massachusetts Institute of Technology! p. 31<br />

Participants<br />




Gloomy planets: overcoming remote sensing challenges for cloudy atmospheres<br />

Joanna K. Barstow — University of Oxford<br />

For most known planets, our only knowledge about their atmospheres comes from remote<br />

sensing and spectroscopic analysis. There are often multiple, degenerate atmospheric<br />

states that could produce the observed spectra, and usually more complex atmospheric<br />

models result in greater numbers of permitted atmospheric states. The inclusion of clouds<br />

in an atmospheric model increases its complexity. The size of the cloud parameter space,<br />

the nature of the condensate, size of condensate particles, number density and location<br />

within the atmosphere all influence spectral features.<br />

Recent analyses of the best-studied extrasolar planets, such as HD 189733b and GJ<br />

1214b, indicate that clouds are as ubiquitous outside the solar system as they are inside it.<br />

Their probable presence on these planets can no longer be ignored, but the quality and<br />

spectral coverage of remote sensing data for exoplanets and the outer planets in our own<br />

solar system limits our ability to draw conclusions about their nature. We are left with a<br />

vast, underconstrained model parameter space to explore. In addition, the presence of<br />

uncharacterised clouds in planetary atmospheres can prevent us from placing constraints<br />

on temperature structure and chemistry due to model degeneracy, or can result in<br />

mistaken conclusions based on incorrect assumptions.<br />

I explore the significance of different cloud properties for reflection, emission and<br />

transmission spectra of planetary atmospheres, including examples such as the extremely<br />

detailed characterisation of the H2SO4 cloud on Venus, the hints of enstatite clouds on HD<br />

189733b, and the possibility of Titan-like hydrocarbon hazes on GJ 1214b. I will present<br />

suggestions for a framework to explore cloudy solutions for data-poor planets.<br />

The structure of the Intertropical Convergence Zone over a wide range of<br />

atmospheric circulations simulated with an idealized GCM!<br />

Sean Faulk — UCLA!<br />

One of the most prominent features of the Earth's large-scale circulation in low latitudes is<br />

the intertropical convergence zone (ITCZ), where tropical precipitation is concentrated in a<br />

relatively narrow latitudinal band. Given that small changes in the ITCZ can result in large<br />

local changes in precipitation, factors that control its structure and position have been<br />

widely investigated in the literature. In other planetary settings such as Mars and Titan, it<br />

has been argued that an ITCZ can migrate significantly off the equator into the summer<br />

hemisphere, perhaps even to the summer pole. The dynamical, thermodynamical and<br />

radiative mechanisms controlling seasonal ITCZ migrations has only begun to be explored.<br />

Exploration of the ITCZ behavior in a wide parameter space is important to understand the<br />

fundamental dynamics of the Earth's ITCZ and also to characterize climates on other<br />

planets. Here, we examine the structure of the ITCZ over a wide range of atmospheric<br />

* Arranged by topic in six categories. See the list of participants (p.10) to find page of specific abstract<br />


circulations with an idealized General Circulation Model (GCM), in which an atmospheric<br />

model with idealized physics is coupled to an aquaplanet slab ocean of fixed depth and the<br />

top-of-atmosphere insolation is varied seasonally. A broad range of circulation regimes is<br />

studied by changing the thermal inertia of the slab ocean, the planet rotation rate and<br />

radius while keeping the seasonal cycle of insolation fixed. The climates of Earth, Mars<br />

and Titan will be discussed in this context, and implications for classifying exoplanet<br />

climates will be drawn.<br />

A search for hot water vapor in the atmosphere of Venus during the 2012 transit<br />

Daniel Gisler — Kiepenheuer-Institut für Sonnenphysik<br />

We have observed the Venus transit in 2012 using the Scatter-free Observatory for Limb<br />

Active Regions and Coronae (SOLARC), located on the summit of Haleakala, Maui. The<br />

SOLARC is a 45 cm off-axis Gregorian telescope. This telescope design minimizes<br />

scattered light, that is critical for photon-limited observations. The data has been collected<br />

with the Optical Fiber Imaging Spectralpoarimeter (OFIS). Our goal is to search for water<br />

vapor lines absorbing solar light passing through the Venusian atmosphere and evaluate<br />

the sensitivity of our spectropolarimetric technique to detect water and other constituents<br />

in atmospheres of transiting exoplanets. Here we present the data and analyze Stokes I,<br />

Q, U spectra extracted from the solar disk and the Venus limb and night side. We estimate<br />

limits on the water vapor partial pressure and compare these with measurements by space<br />

missions and probes.<br />

Development of a new Global Climate Model of Saturn's stratosphere<br />

Sandrine Guerlet — Laboratoire de Météorologie Dynamique, Paris!<br />

Recent observations of Saturn’s stratospheric thermal structure and composition have<br />

revealed new phenomena: an equatorial oscillation in temperature, reminiscent of the<br />

Earth's Quasi-Biennal Oscillation ; strong meridional contrasts of hydrocarbons ; a warm<br />

“beacon” associated with the powerful 2010 storm. Those signatures cannot be<br />

reproduced by 1D photochemical and radiative models and suggest that atmospheric<br />

dynamics plays a key role. This motivated us to develop a complete 3D General<br />

Circulation Model (GCM) for Saturn, based on the LMD’s hydrodynamical core, to explore<br />

the circulation, seasonal variability, and wave activity in Saturn's atmosphere.<br />

In order to closely reproduce Saturn's radiative forcing, a particular emphasis was put in<br />

obtaining fast and accurate radiative transfer calculations. Our radiative model uses<br />

correlated-k distributions and spectral discretization tailored for Saturn's atmosphere. We<br />

include an internal heat flux, ring shadowing and both tropospheric and stratospheric<br />

aerosols.<br />

Firstly, we will present a comparison of temperature fields obtained with this new<br />

seasonal, radiative equilibrium model to that inferred from Cassini/CIRS observations.<br />

Even in the absence of dynamics, our model qualitatively reproduces the overall<br />

meridional temperature gradient between the summer and the winter hemispheres in the<br />

lower stratosphere except in the equatorial region, where the temperature structure is<br />

governed by the dynamical equatorial oscillation. Our model can also reproduce the<br />

“temperature knee” observed around 200 mbar, which is caused by heating at the top of<br />

the tropospheric aerosol layer.<br />


Finally, we will show GCM simulations coupling the 3D dynamical core to this radiative<br />

model, and discuss the large-scale stratospheric circulations driven by the radiative<br />

forcing.<br />

Simulated transit spectra of Earth and Jupiter<br />

Patrick Irwin — University of Oxford<br />

In recent years, increasingly accurate measurements have been made of the transit<br />

spectra of hot Jupiters, such as HD 189733b, from the visible through to mid-infrared<br />

wavelengths. These have been modelled to derive the likely atmospheric structure and<br />

composition of these planets. As measurement techniques improve, the transit spectra of<br />

super-Earths such as GJ 1214b are becoming increasingly accessible, allowing model<br />

atmospheric states to be fitted for this class of planet also. While it is not yet possible to<br />

constrain the atmospheric states of solar system-like planets such as the Earth or Jupiter<br />

from such measurements, it is hoped that this might one day become practical; if so, it is of<br />

interest to determine what we might infer from such measurements. In this work we have<br />

constructed atmospheric models of Earth and Jupiter from 0.2 - 15 microns that are<br />

consistent with ground-based and satellite observations. From these models we calculate<br />

the primary and secondary transit spectra (with respect to the Sun) that would be observed<br />

by a remote observer, many light years away, and also directly imaged spectra, assuming<br />

that this one day becomes technically feasible. From these spectra we test how well<br />

optimal estimation retrieval models can determine the atmospheric states and compare<br />

these with the “ground truths” in order to assess: a) the inherent difficulty in using transit<br />

spectra observations to observe solar system-like targets; b) the relative merits of primary<br />

versus secondary transit spectra; and c) the optimal wavelength coverage, resolutions and<br />

sensitivities required to retrieve useful information about the atmospheres of such planets.<br />

D/H ratios in methane in the atmosphere of giant planets and Titan!<br />

Lucyna Kedziora-Chudczer — University of New South Wales<br />

We present observations of the GNIRS/GEMINI high resolution spectra at 1.58 and 2.03<br />

microns for the giant planets of our Solar System and Saturn's moon Titan. We fitted the<br />

atmospheric absorption spectra of these objects using the VSTAR line-by-line radiative<br />

transfer modelling to estimate the D/H ratios from deuterated methane in both bands.<br />

Deuteration of the outer planets can be used not only as a diagnostic of initial conditions in<br />

the solar nebula during formation of giant planets but also to help to determine the location<br />

at which planets accreted the bulk of their mass. We estimated that based on D/H ratio<br />

derived for Titan, the Saturnian system formed close to its current location, which has<br />

implication on previously proposed migration theories.<br />

Vertical structure of gas-planet atmospheres inferred from methane bands<br />

Nadiia Kostogryz — Kiepenheuer-Institut für Sonnenphysik<br />

Visible and near infrared spectra of the Jovian planets in the Solar system are dominated<br />

by methane absorption features. These bands are very useful for determining the vertical<br />

cloud structure of planetary atmospheres as was proposed by Morozhenko (1984) and<br />

implemented for the Uranus atmosphere by Kostogryz (2013). The fact that the diffusely<br />

reflected radiation is formed at different effective depths in the atmosphere allows to<br />

constrain the vertical cloud structure. The cloud height and opacity strongly influence the<br />


geometric albedo of the planet and, therefore, are needed for constructing a realistic<br />

atmosphere model. Here we extend this method to exoplanetary atmospheres. We<br />

simulate methane spectra from atmospheres with various cloud structure and analyze<br />

them as observed spectra to infer the cloud properties. We investigate limits on the<br />

spectral resolution and signal-to-noise ratio for this technique to be applied to hot Jupiter<br />

atmospheres.<br />

Atmospheric super-rotation in solar system and extra-solar planetary atmospheres<br />

Stephen R. Lewis — The Open University, UK<br />

Super-rotation is a common phenomenon in solar system planetary atmospheres. Out of<br />

the four substantial atmospheres possessed by solid bodies in the solar system, the slowly<br />

rotating planet, Venus, and moon, Titan, are both well-known to have atmospheres that<br />

rotate on average substantially more quickly than does the solid surface underneath. The<br />

more rapidly rotating planets, Mars and Earth, have much weaker global super-rotation,<br />

but both can exhibit time-varying prograde jets near the equator which rotate more rapidly<br />

than the local surface. Atmospheric super-rotation is not restricted to planets with solid<br />

surfaces and shallow atmospheres. Cloud-tracking observations of the gas giants Jupiter<br />

and Saturn show that they both possess rapid prograde equatorial jets and hence exhibit<br />

local super-rotation.<br />

Simplified global circulation models of extra-solar planets, including representations of<br />

hot Jupiters and Earth-like planets rotating at different rates, can also show sustained<br />

super-rotating equatorial jets in different dynamical regimes. In the extra-solar planet<br />

cases in particular, the quantitative results are highly sensitive to model parameters.<br />

In each case the detailed mechanism, or combination of mechanisms, which produces<br />

the super-rotating jets might vary, but all require longitudinally asymmetric motions, waves<br />

or eddies, to transport angular momentum up-gradient into the jets. The mechanism is not<br />

always easy to diagnose from observations and requires careful modelling. We review<br />

both observations of solar system planets and recent global circulation model results,<br />

combined in the case of Mars and Earth in the form of atmospheric reanalyses by data<br />

assimilation, together with simplified extra-solar planet simulations.<br />

Generation and early evolution of Titan's atmosphere<br />

Nadejda Marounina! — LPGN!<br />

Titan is the only satellite of the Solar System with a substantial atmosphere (1.47 bar),<br />

which is primarily composed of N2 (~98%) and CH4 (~ 2%). The low Ar/N2 ratio measured<br />

by the Huygens probe in Titan's atmosphere indicates that the nitrogen was incorporated<br />

as NH3 and possibly other nitrogen-bearing easily condensible compounds. Therefore, a<br />

conversion mechanisms is needed to explain the present-day N2-dominated atmosphere.<br />

Different conversion scenarios have been proposed (endogenic conversion, atmospheric<br />

impact chemistry...). Here we evaluate a scenario recently proposed by Sekine et al.<br />

(2011) involving an impact-induced conversion of NH3, stored as hydrate in Titan’s icy<br />

crust, and subsequent degassing of N2 during the Late Heavy Bombardement. Using the<br />

scaling laws derived from their experimental study, we computed the balance between the<br />

degassed N2 and the erosion of the atmosphere by impact (Shuvalov 2009) for an impact<br />

population characteristic of the Late Heavy Bombardment (LHB). Our numerical model<br />

include a parameterized description of the radiative and thermodynamical equilibria of the<br />

atmosphere (Lorenz et al. 1999).<br />


Our results show that whatever the size of NH3-enriched crustal reservoirs, N2 production<br />

by impacts is not able to counterbalance the atmospheric loss by impact erosion for<br />

realistic size distribution of impactors. We show that in order to preserve a substantial<br />

atmosphere on Titan after the LHB, an initially massive atmosphere (5-times present-day<br />

mass) is required. Our results indicate that a very efficient conversion mechanism should<br />

have occurred during the accretion and shortly after to produce such a massive N2<br />

atmosphere.<br />

During accretion the impact heating may have been strong enough to melt the superficial<br />

icy layer and form an ocean, which volatile species outgassed and form a primitive<br />

atmosphere (Monteux et al., in prep). We are currently developing a new numerical model<br />

of a liquid-vapor equilibrium for various initial oceanic composition to investigate how a<br />

massive atmosphere may be generated during the satellite growth and how it may then<br />

evolve toward a composition dominated by N2. More generally, our model may address<br />

how atmosphere may be generated in water-rich objects, which may be common around<br />

other stars.<br />

Simulating the atmospheric circulation of Venus!<br />

Joao Mendonca — University of Bern!<br />

Venus is the most Earth-like astronomical object in terms of size, mass and orbital<br />

properties in our Solar system. Despite these similarities, Venus is slowly rotating in the<br />

opposite direction, has the most massive atmosphere of the terrestrial planets and is<br />

covered by an opaque and highly reflective cloud layer. These differences are important to<br />

drive the Venus atmospheric circulation to a very distinct regime from Earth's, with strong<br />

atmospheric super-rotation and a variety of other atmospheric dynamic features such as<br />

the observed large-scale wave patterns, which are not well understood.<br />

I will summarise the main efforts of the last three decades to simulate the Venus<br />

atmospheric circulation using general circulation models, and the most likely mechanisms<br />

driving the atmosphere to the actual observed circulation. Recently in Lebonnois et al.<br />

2011, it was shown that Venus general circulation models that use simplified<br />

representations of heating, cooling and friction processes, obtained very distinct results,<br />

which raised concerns about the intrinsic numerical errors and assumptions in the routines<br />

that solve the dynamical behaviour of the flow. These problems and the latest results by<br />

modern models, which use more physically-based parameterizations (Lebonnois et al.<br />

2010 & Mendonca 2013) will be discussed and compared. In our new model (Mendonca<br />

2013), the Venus atmospheric circulation in the cloud region is well represented.<br />

Additionally, the results are sensitive to some radiative properties near the surface and<br />

also to the amount of clouds. Despite the progress, there are still modelling difficulties<br />

which I will address in this work. I will also analyse and describe the main implications that<br />

the Venus climate modelling has in the exploration of exo-climes.<br />

Transmission spectra of Jupiter from Ganymede during eclipses!<br />

Pilar Montañès-Rodrìguez — Instituto de Astrofìsica de Canarias !<br />

Transit spectroscopy data from several hot Jupiter planets are already being collected from<br />

several space and ground-based instruments. And more temperate Jupiter-like planets are<br />

expected to be characterized in the near future. In this framework, an investigation of the<br />

spectral features of Jupiter, in transmission, as if it were observed from a distant star, can<br />

greatly contribute to the modeling efforts of such planetary atmospheres. Here, we present<br />

observations of the near-infrared transmission spectrum of Jupiter with LIRIS at the WHT,<br />


as reflected from Ganymede's surface during an eclipse. When Ganymede is in the umbra<br />

of Jupiter, only sunlight that has traversed the Jupiter atmosphere is illuminating its<br />

surface. By taking observations of Ganymede before and during an eclipse, we are able to<br />

retrieve Jupiter's atmospheric fingerprints.<br />

Disk-integrated reflection light curves of planets!<br />

Antonio Garcìa Muñoz — ESA-RSSD, ESTEC<br />

The light scattered by a planet atmosphere contains valuable information on the planet’s<br />

composition and aerosol content. Typically, the interpretation of that information requires<br />

elaborate radiative transport models accounting for the absorption and scattering<br />

processes undergone by the star photons on their passage through the atmosphere. I<br />

have been working on a particular family of algorithms based on Backward Monte Carlo<br />

(BMC) integration for solving the multiple-scattering problem in atmospheric media. BMC<br />

algorithms simulate statistically the photon trajectories in the reverse order that they<br />

actually occur, i.e. they trace the photons from the detector through the atmospheric<br />

medium and onwards to the illumination source following probability laws dictated by the<br />

medium’s optical properties. BMC algorithms are versatile, as they can handle diverse<br />

viewing and illumination geometries, and can readily accommodate various physical<br />

phenomena. As will be shown, BMC algorithms are very well suited for the prediction of<br />

magnitudes integrated over a planet’s disk (whether uniform or not). Disk-integrated<br />

magnitudes are relevant in the current context of exploration of extrasolar planets because<br />

spatial resolution of these objects will not be technologically feasible in the near future. I<br />

have been working on various predictions for the disk-integrated properties of planets that<br />

demonstrate the capacities of the BMC algorithm. These cases include the variability of<br />

the Earth’s integrated signal caused by diurnal and seasonal changes in the surface<br />

reflectance and cloudiness, or by sporadic injection of large amounts of volcanic particles<br />

into the atmosphere. Since the implemented BMC algorithm includes a polarization mode,<br />

these examples also serve to illustrate the potential of polarimetry in the characterization<br />

of both Solar System and extrasolar planets. The work is complemented with the analysis<br />

of disk-integrated photometric observations of Earth and Venus drawn from various<br />

sources.<br />

Comparative global energy budgets for the climates of terrestrial and gas giant<br />

planets<br />

Peter Read — University of Oxford<br />

The weather and climate on Earth are generally determined by the amount and distribution<br />

of incoming solar radiation. This must be balanced in equilibrium by the emission of<br />

thermal radiation from the surface and atmosphere, but the precise routes by which<br />

incoming energy is transferred from the surface, through the atmosphere and back out to<br />

space are important features that characterize the current climate. This has been analysed<br />

by several groups over the years, based on combinations of numerical model simulations<br />

and direct observations of the Earth’s climate system. The results are often presented in<br />

schematic form (Trenberth et al. 2009) to show the main routes for the transfer of energy<br />

into, out of and within the climate system. Although relatively simple in concept, such<br />

diagrams convey a great deal of information about the climate system in a compact form,<br />

and are especially valuable pedagogically at school and undergraduate level.<br />

Such an approach has not so far been adopted in any systematic way for other planets of<br />

the Solar System, let alone beyond, although quite detailed climate models of several<br />


planets are now available, constrained by many new observations and measurements.<br />

Here we analyse the global transfers of energy within the climate systems of a range of<br />

terrestrial planetary bodies within the Solar System, including Mars, Titan and Venus, as<br />

simulated by relatively comprehensive numerical circulation models. These results will<br />

then be presented in schematic form for comparison with the “classical” global energy<br />

budget analysis of Trenberth et al. for the Earth, highlighting the important similarities and<br />

differences. We also consider how to extend this approach towards other Solar System<br />

and extra-solar planets, including Jupiter, Saturn and hot Jupiter exoplanets.<br />

A ~0.1 bar Rule for Tropopause Temperature Minima in Thick Atmospheres of<br />

Planets and Large Moons<br />

Tyler Robinson — University of Washington<br />

Tropopause temperature minima are fundamental for understanding planetary atmospheric<br />

structure. Inversions in the stratospheres of Earth, Jupiter, Saturn, Titan, Uranus, and<br />

Neptune lead to temperature minima that, remarkably, all occur near 0.1 bar, despite very<br />

different insolation, atmospheric composition, gravity, and internal heat flux. We have<br />

explored this common 0.1 bar tropopause using an analytic 1-D radiative-convective<br />

model. We find that tropopause temperature minima always lie in the radiative regime,<br />

above the radiative-convective boundary. Thus, the shared 0.1 bar tropopause arises from<br />

the common physics of radiative transfer. Model fits to solar system worlds show that the<br />

gray infrared optical depth where the tropopause minimum occurs is ~0.1. Furthermore,<br />

the gray infrared optical depths at a pressure of 1 bar are typically of order a few. These,<br />

along with a commonly used power-law scaling between pressure and optical depth, set<br />

the tropopause pressure at ~0.1 bar. Moving beyond the solar system, we show that the<br />

typical gray infrared optical depth of the tropopause minimum is ~0.1 for a wide range of<br />

plausible atmospheric compositions. This optical depth marks the transition into an upper<br />

region of an atmosphere that is very transparent to thermal radiation. Here, shortwave<br />

absorption can dominate the temperature profile and, thus, create an inversion and<br />

corresponding temperature minimum. These findings imply that the common 0.1 bar<br />

tropopause levels seen in the solar system atmospheres are more universal. Thus, we<br />

hypothesize that many exoplanets will possess a 0.1 bar tropopause temperature<br />

minimum.<br />

Measurement of the atmospheres of Europa, Ganymede, and Callisto<br />

Peter Wurz — Physics Institute, University of Bern!<br />

The regular Jovian satellites are believed to be formed at the end of Jupiter's formation<br />

epoch, from the collisional accretion of solids originating in the Solar Nebula, and captured<br />

in a disk orbiting around the planet. The solids taking part to the formation of the satellites<br />

therefore originate from the initial protoplanetary disk, and have probably experienced<br />

lower temperature and pressure conditions as has the material incorporated in Jupiter, and<br />

their chemical composition has been probably less altered. By measuring the composition<br />

of the Jovian satellites, it is therefore possible to set constraints on the chemical<br />

composition of building blocks of planets and satellites, and ultimately on the<br />

thermodynamical conditions in the Solar Nebula.<br />

The Particle Environment Package (PEP) suite has been selected for the JUICE mission<br />

of ESA, which contains instruments for the comprehensive measurements of electrons,<br />

ions and neutrals. One of the instruments is the Neutral and Ion Mass spectrometer<br />

instrument (NIM). NIM is a time-of-flight neutral gas and thermal ion mass spectrometer<br />


optimised for exospheric investigations. NIM will measure the composition of the<br />

exospheres of Europa, Ganymede, and Callisto. Various physical processes are acting on<br />

the surfaces of Jupiter’s icy moons to promote material from the surface into the<br />

exosphere. These are thermal desorption (sublimation), photon stimulated desorption, ioninduced<br />

sputtering, and micro-meteorite impact vaporisation, with sputtering being the<br />

most important surface release process. Sputtering releases all species present on the<br />

surface more or less stoichiometrically into the exosphere, allowing deriving the chemical<br />

composition of the surface from these measurements. However, the chemical composition<br />

of the surface is modified by the bombardment of energetic electrons and ions, and<br />

ultraviolet radiation, which has to be accounted for in the chemical analysis.<br />

High-resolution and high-SNR transmission spectrum of Earth’s atmosphere<br />

obtained from a lunar eclipse!<br />

Fei Yan — European Southern Observatory & National Astronomical Observatories,<br />

Chinese Academy of Sciences!<br />

With the rapid developments in the exoplanet field, more and more terrestrial exoplanets<br />

are being detected. Characterising their atmospheres using transit observations will<br />

become a key datum in the quest for detecting an Earth-like exoplanet. The atmospheric<br />

transmission spectrum of our Earth will be an ideal template for comparison with future<br />

exo-Earth candidates. By observing a lunar eclipse, which offers a similar configuration to<br />

that of an exoplanet transit, we have obtained a high resolution and high signal-to-noise<br />

ratio transmission spectrum of the Earth’s atmosphere.<br />

We will present the transmission spectrum together with our 1-D atmospheric spectral<br />

model. From the model-fit, the column densities of the various atmospheric species are<br />

calculated. Some intersting results from this work are discussed, such as the forwardscattered<br />

sunlight, the oxygen isotopes, the souces of NO2.<br />

Extreme Planetary Classes in Our Own Solar System: The Atmospheric Circulation<br />

of Pluto and Triton!<br />

Angela Zalucha — SETI Institute!<br />

Pluto and Triton (Neptune's largest moon) are often called “sister worlds” due to their<br />

nearly identical atmospheric composition, size, and temperature. While the bulk<br />

temperature and composition have been constrained by ground-based stellar occultation<br />

observations and the Voyager 2 flyby of Neptune, the circulation patterns at all scales are<br />

still not known due to the difficulty in observing wind remotely. Pluto and Triton, or “ice<br />

dwarfs”, are quite unusual compared with other known planetary bodies, in that efficient<br />

methane absorption in the atmosphere creates at strong temperature inversion<br />

(temperature increasing with height) near the surface that has been dubbed the<br />

stratosphere. Such a configuration is extremely stable and prevents vertical motion, which<br />

impacts flow in the other directions as well (for example, Hadley cells, ubiquitous on<br />

terrestrial planets and perhaps super-Earths, are not expected to exist). Moreover, much<br />

like Mars, it is thought that these sister worlds have a volatile cycle where the main<br />

atmospheric constituent (here molecular nitrogen) condenses and sublimates throughout<br />

the year, even to the point of atmospheric collapse.<br />

Within the past few years, there has been a surge of interest in Pluto's global circulation<br />

patterns. This problem has posed a challenge unprecedented from other planetary bodies.<br />

First, Pluto's year is about 250 Earth years, requiring long simulation times.Second, Pluto's<br />

atmosphere and surface are thought to be strongly coupled radiatively, requiring both a<br />


sophisticated atmosphere and surface model. The properties (emissivity, configuration of<br />

ices, thermal inertia, and total surface ice inventory) of Pluto's surface are not well<br />

constrained. Various groups have used different general circulation models (GCMs) to<br />

predict the atmospheric circulation of Pluto. I will discuss results from the MIT Pluto GCM,<br />

which after several years of atmosphere-only studies (e.g. Zalucha and Michaels 2013) is<br />

now coupled to a sophisticated surface model.<br />


Maximum planet size for habitability<br />

Yann Alibert! — University of Bern<br />

The conditions that a planet must fulfill in order to be habitable are not precisely known.<br />

However, it is comparatively easier to define conditions under which a planet is very likely<br />

not habitable. Finding such conditions is moreover important as it can help to select, in an<br />

ensemble of potentially observable planets, which ones should be observed in more<br />

details for characterization studies. Assuming, as in the case of the Earth, that the<br />

presence of a C-cycle is a necessary condition for long-term habitability, we derive, as a<br />

function of the planetary mass, a radius above which a planet is likely not habitable. For<br />

this, we compute the maximum radius a planet can have in order to fulfill two constraints:<br />

surface conditions compatible with the existence of liquid water, and no ice layer at the<br />

bottom of a putative global ocean. We demonstrate that, above a given radius, these two<br />

constraints cannot be met. For this, we compute internal structure models of planets, using<br />

a 5-layer model (core, inner mantle, outer mantle, ocean and atmosphere), for different<br />

masses and composition of the planets (in particular Fe/Si ratio of the planet). Our results<br />

show that for planets in the Super-Earth mass range (1-12 Mearth), the overall maximum<br />

size that a planet can have varies between 1.8 and 2.3 Rearth. This radius is reduced when<br />

considering planets with higher Fe/Si ratios, and taking into account irradiation when<br />

computing the gas envelope structure.<br />

Remote detection of biosignatures on Earth-like planets<br />

Svetlana Berdyugina — KIS, Freiburg<br />

Life on Earth is aware of light polarization and makes good use of it for its survival and<br />

growth. In all cases, it is the solar light that is reflected, processed and analyzed by life<br />

forms, and the same circumstances are expected to exist on all habitable planets.<br />

Photosynthesis, in particular, is very likely to arise on another planet and can produce<br />

conspicuous biosignatures. Recently, it was demonstrated that polarized reflected light can<br />

be detected from exoplanetary atmospheres. We focus now on identifying biological<br />

polarization effects, e.g., selective light absorption or scattering by biogenic molecules.<br />

This helps to enhance the reliability of other biomarkers for distant detection of life which<br />

can be contaminated by non-biological sources. Here we present a laboratory study of<br />

reflected light polarization from various terrestrial plants and non-biological samples (rocks<br />

and sands). We use these measured reflection spectra to synthesize polarized spectra of<br />

Earth-like planets with various contributions from the land, photosynthetic organisms,<br />

ocean, atmosphere, and clouds. We estimate the required photometric and polarimetric<br />

sensitivity to detect such planets in habitable zones of nearby stars.<br />


Weather on strange new worlds: Large scale atmospheric dynamics on tidally<br />

locked terrestrial planets around an M dwarf star<br />

Ludmila Carone — KU Leuven, Center for mathematical Plasma-astrophysics<br />

!<br />

It is likely that the first habitable extrasolar planet with an atmosphere will be discovered<br />

around an M star. Indeed, several terrestrial planets have already been discovered around<br />

such stars. These planets will probably be tidally locked. Therefore, the climate dynamics<br />

of a terrestrial exoplanet — even in the habitable zone — might be very different from the<br />

Earth. Firstly, the rotation will be slower and we would therefore not expect mid-latidude<br />

cyclones but rather a barotropic atmosphere. Secondly, the temperature varies rather with<br />

longitude than with latitude leading to circulation between the dark and cold hemisphere.<br />

Because there are many unknowns with exoplanets, in particular with terrestrial<br />

exoplanets, we decided to explore the dynamics of a greenhouse atmosphere on a tidally<br />

locked planet with a medium-size parameter study. We used an idealized global threedimensional<br />

dry circulation model (GCM) with an idealized forcing, adopting MITgcm<br />

(http://mitgcm.org). As a first step, different day-night temperature differences, rotation<br />

periods, time scales for radiation and surface friction, and surface pressures were<br />

investigated. The emerging large scale dynamics of the atmosphere was compared with<br />

previous studies and with observations and models of Venus and Titan; the latter being the<br />

closest analogues in the Solar System. Our goal is to identify, on the one hand, features<br />

that are robust against parameter change — like superrotation and Hadley-like circulation<br />

cells — and, on the other hand, to investigate climate patterns that vary strongly with<br />

different assumptions: like the surface wind and temperature, and large scale vortices.<br />

This not only broadens our understanding about the different mechanisms at play in<br />

atmospheres, but may also lead to a better coupling between observations of transiting<br />

terrestrial exoplanets and atmospheric models.<br />

The Prospects for Characterizing the Atmospheres of Rocky Exoplanets!<br />

David!Charbonneau — Harvard University!<br />

The coming decade brings the promise of direct spectroscopic characterization of the<br />

atmospheres of rocky planets orbiting other nearby stars. The most accessible planets will<br />

be those that orbit M-dwarfs, owing to the diminutive stature, low-luminosities, and<br />

preponderance of these stars. This talk will present a quantitative evaluation of the<br />

prospects for this path informed by the most recent data: I will begin by presenting an<br />

analysis of the complete Kepler dataset to determine the rate of occurrence of such<br />

planets. I will combine this with the catalog of nearby stars to evaluate the likely distance<br />

to the closest transiting systems, and the likely characteristics of the stellar host. I will then<br />

address the sensitivity of the NASA TESS Mission, the MEarth transit survey, and other<br />

ongoing projects to detect such objects. I will conclude by presenting the likely signal-tonoise,<br />

resolution, and wavelength coverage that should be delivered by the James Webb<br />

Space Telescope, the Giant Magellan telescope, and other large ground-based<br />

telescopes. Using the technique of transmission spectroscopy, some of these telescopes<br />

should be able to investigate such planetary atmospheres beginning as early as 2018,<br />

provided the community has identified the targets. The goal of this presentation will be to<br />

leave the audience with a quantitative understanding of what we can, and cannot, hope to<br />

measure in this time frame, and thus to assist them in directing their research efforts<br />

accordingly.<br />


Exoplanetary Extreme Space Weather<br />

Ofer Cohen — Harvard-Smithsonian CfA!<br />

Exoplanetary research is driven by the ultimate goal of defining whether life can exist<br />

beyond the Earth and the solar system, while recent searches for exoplanets are focused<br />

increasingly on detecting rocky, Earth-like planets around M-dwarf stars, which are by far<br />

the most numerous type of star in the Universe. The “planet habitability” problem is a<br />

cross-disciplinary topic where commonly, a planet is defined as habitable if its surface<br />

temperature allows water to exist in a liquid form. However, there are other factors that can<br />

impact planet habitability. M-dwarf stars are very active magnetically and their X-ray and<br />

ultraviolet radiation in their habitable zones is much higher than we experience near the<br />

Earth.<br />

The physics of the solar atmosphere, the interplanetary environment, and the upper<br />

atmospheres of planets in the solar system, including the Earth, is governed by the<br />

radiation environment, electromagnetic forces, and the interaction between charged<br />

particles and magnetic fields. In particular, the atmosphere of the Earth is shielded from<br />

the intense radiation in space and from the solar wind by the Earth’s intrinsic magnetic<br />

field. Here we present a set of numerical models, which were developed to study solar<br />

system objects, and their application to exoplanetary, M-dwarf systems. These models<br />

include detailed physical processes that are known to be important for solar system<br />

bodies, but are commonly neglected in the context of exoplanets. Specifically, we<br />

investigate the role of the planetary magnetic field in shielding the planetary atmosphere<br />

from erosion by the extreme space environment in which it resides. Our study estimates<br />

what planetary field strengths are necessary for protection from the caustic space<br />

environment of M-dwarfs, and demonstrates how coronal mass ejections from M-dwarfs<br />

affects the planet’s magnetospheres, and how much atmosphere is likely to be stripped<br />

away in the larger events.<br />

Defining Habitable Zones in Gravitationally Interacting Systems!<br />

Siegfried Eggl — IMCCE Observatoire de Paris!<br />

Calculating the extent of liquid-water habitable zones around main sequence stars<br />

becomes challenging for systems with more than two gravitationally interacting bodies,<br />

since the evolution of planetary orbits has to be taken into account. Given the recent<br />

progress in determining liquid-water habitable zones within binary star systems we present<br />

a generalized methodology to identify habitable-zone boundaries in multistar and<br />

multiplanet systems.<br />

Planning follow-up Space Missions searching for Atmospheric Spectral<br />

Biosignatures from a sample of potentially habitable Earth-like Exoplanets!<br />

John Lee Grenfell — Planetary Research Inst. DLR Berlin!<br />

Next generation missions which aim at the atmospheric characterization of rocky<br />

extrasolar planets could provide initial information on the amounts of carbon dioxide and<br />

water molecules in the atmospheres of hot to temperate Super-Earths. Follow-up studies<br />

may be needed however to search for (likely weaker) atmospheric biosignature signals<br />

from a sample of Super-Earths. Until now, most studies have focused on the effects of<br />

atmospheric carbon dioxide and water upon planetary climate, hence (potential)<br />

habitability. There is, however, potentially additional information held in such data. On<br />


Earth, atmospheric carbon dioxide is strongly affected by life itself (e.g. vegetation<br />

enhances weathering) so that on a “dead Earth” the atmospheric carbon dioxide would be<br />

significantly higher than on its living counterpart. This could represent an additional<br />

selection procedure for follow-up studies searching for biosignatures from a sample of<br />

habitable planets. A difficult challenge when applying such a technique is to constrain<br />

abiotic processes affecting atmospheric carbon dioxide e.g. hydrology, geochemistry and<br />

outgassing. Life itself may also regulate the carbon-silicate cycle, hence stabilize climate,<br />

but the extent and means of this process if it exists are not well known. Forty years ago a<br />

cluster of studies focused on “live” and “dead” Earths in the context of the Gaia hypothesis<br />

and the effect on the carbon cycle. There is now a need to revisit this work with newgeneration<br />

models but with a focus on exoplanetary habitability. In this work we discuss<br />

possible selection procedures for follow-up studies which search for biosignatures given a<br />

sample of rocky Super-Earths with known atmospheric carbon dioxide and water<br />

abundances. We apply a radiative column model to calculate consistent CO2 and H2O<br />

abundances for dead Earth scenarios.<br />

The role of ocean heat transport in climates of tidally locked exoplanets around M-<br />

dwarf Stars<br />

Yongyun Hu! — Peking University!<br />

The distinctive feature of tidally locked exoplanets is the very uneven heating by stellar<br />

radiation between the dayside and nightside. Previous work has focused on the role of<br />

atmospheric heat transport in preventing atmospheric collapse on the nightside for<br />

terrestrial exoplanets in the habitable zone around M-dwarfs. In the present paper, we<br />

carry out the first simulation with a fully coupled atmosphere-ocean general circulation<br />

model (AOGCM) to investigate the role of ocean heat transport in climate states of tidally<br />

locked habitable exoplanets around M-dwarfs. Our simulation results demonstrate that<br />

ocean heat transport substantially extends the area of open water along the equator,<br />

showing a lobster-like spatial pattern of open water, instead of an “eyeball”. For sufficiently<br />

high-level greenhouse gases or strong stellar radiation, ocean heat transport can even<br />

lead to complete deglaciation of the nightside. Our simulations also suggest that ocean<br />

heat transport likely narrows the width of M-dwarfs’ habitable zone. This study provides the<br />

first demonstration of the importance of exo-oceanography in determining climate states<br />

and habitability of exoplanets.<br />

Updates to the SPARC/MITgcm: Modeling the atmospheric circulation of terrestrial<br />

exoplanets!<br />

Tiffany Kataria — University of Arizona<br />

As the detection and characterization of exoplanets moves toward smaller planets in the<br />

super-Earth and terrestrial regimes, atmospheric circulation modeling continues to play an<br />

important role in helping to understand ground-and space-based observations of their<br />

atmospheres. These models must range from planets with thick atmospheric envelopes<br />

and no surface (for super Earths) to planets with thinner atmospheres and rocky surfaces<br />

(for terrestrial exoplanets). To that end, we present a summary of terrestrial planet updates<br />

to our model, the Substellar and Planetary Atmospheric Radiation and Circulation<br />

(SPARC) model, which couples the MIT General Circulation Model with a two-stream, nongrey<br />

implementation of the multi-stream, non-grey radiative transfer code developed by<br />

Marley and McKay (1999). These updates include an implementation of moist and dry<br />

convective schemes, a boundary layer scheme, and a surface energy balance which self-<br />


consistently calculates the ground temperature. We present early results from studies<br />

looking at the role of clouds on the dynamics and habitability of terrestrial exoplanets<br />

orbiting M-dwarfs. Using these models, we will identify fundamental dynamical<br />

mechanisms that drive their atmospheres and constrain their thermal structures, which will<br />

inform future observations of transiting terrestrial exoplanets, particularly at secondary<br />

eclipse.<br />

Modeling of Habitable Planets - the Underlying Atmospheric Dynamics<br />

Cevahir Kilic! — University of Bern!<br />

Instrumentation to detect new planets develops continually and enabled the scientific<br />

community to characterize exoplanets in terms of physical parameters, such as size and<br />

mass, as well as identify possible atmospheres. Furthermore, the CHEOPS satellite<br />

program will provide the possibility for an improved characterization also in terms of<br />

habitability of exoplanets. The increasing number of newly detected planets raises issues<br />

of possible other habitable worlds.<br />

To investigate the atmospheric dynamics of habitable planets, we use a hierarchy of<br />

general circulation models (GCMs). In a first step, we carry out these simulations using a<br />

three-dimensional atmospheric GCM of intermediate complexity, the so-called Planet<br />

Simulator.<br />

For this study, sensitivity simulations varying different basic parameters of the planet are<br />

performed to explore the range of habitability. Each simulation is carried out over 30 model<br />

years. In doing so, we have modified gravity, radius, sidereal day, atmospheric<br />

composition, distance to the star, and obliquity of the ecliptic. These simulations uses an<br />

Earth-like environment (e.g., Earth land mask), which allows us to compare our<br />

investigations with Earth observations. The range of surface temperatures determines the<br />

habitability of a planet. Our simulations show, inter alia, that an increase in radius leads to<br />

a reduction of the global mean temperature. We also find an impact on the amplitude of<br />

the seasonality given by the gravity of the planet. The difference between maximum and<br />

minimum temperature is enhanced with increasing gravity. Additionally, the variation of the<br />

gravity changes the atmospheric structure: an increased gravity leads to a more stable<br />

atmosphere above 700 hPa and to generally stronger wind fields and lower surface<br />

temperatures on the planet. Furthermore, basic dynamical features such as the number of<br />

jet streams will be assessed in the sensitivity simulations. The next steps also include a<br />

model adaption with different land masks (e.g., aqua-planet).<br />

A new perspective on the inner edge of the habitable zone: 3D modeling of runaway<br />

greenhouse processes on Earth like planets<br />

Jeremy Leconte — LMD (Paris) / CITA (Toronto)<br />

Because current exoplanets detection methods are biased toward shorter-period orbits,<br />

most planets discovered to date have a higher equilibrium temperature than the Earth. If<br />

water is available at the surface, the amount of water vapor is expected to increase as the<br />

planet warms, enhancing, in turn, the atmospheric greenhouse effect.<br />

It has been shown that, above a certain critical insolation, this destabilizing greenhouse<br />

feedback can "runaway" until all the oceans are evaporated. It has also been suggested<br />

that warming may sufficiently increase stratospheric humidity to cause oceans to escape<br />

to space before the runaway greenhouse occurs. However, the value of the critical<br />

insolations triggering these processes remain uncertain because they have so far been<br />

evaluated with unidimensional models that cannot account for dynamical effects and cloud<br />


feedback that are key stabilizing features of planetary climates. Understanding and<br />

modeling these processes is thus critical to accurately determine the extent of the<br />

"Habitable Zone" around other stars.<br />

We present results from a 3D global climate model specifically developed to describe hot,<br />

extremely moist atmospheres to quantify Earth like planets climate response to an<br />

increased insolation. In contrast with previous studies, we find that clouds have a<br />

destabilizing feedback on the long term warming. However, subsident, unsaturated regions<br />

created by the Hadley circulation have a stabilizing effect that is strong enough to defer the<br />

runaway greenhouse limit to higher insolation than inferred from 1D models. Because of<br />

these unsaturated regions, the stratosphere remains cold and dry enough to hamper<br />

atmospheric water escape, even at large fluxes.<br />

Finally, we will discus the implications of these results for Venus early water history and<br />

the extent of the habitable zone around low mass stars when the rotation of the planet can<br />

be tidally synchronized.<br />

Terrestrial planet atmospheres in the aftermath of giant impacts!<br />

Roxana Lupu — SETI Institute!<br />

The final assembly of terrestrial planets is now universally thought to have occurred<br />

through a series of giant impacts, such as Earth's own Moon-forming impact. After the<br />

impact the surface of the surviving planet can remain hot for millions of years, making it<br />

potentially detectable by direct imaging surveys. Here we explore the atmospheric<br />

structures and spectral signatures of post-giant-impact terrestrial planets enveloped by<br />

thick atmospheres derived from vaporized rock material. The atmospheric chemistry is<br />

computed self-consistently for compositions reflecting either the bulk silicate Earth (BSE,<br />

including the crust, mantle, atmosphere and oceans) or Earth's continental crust (CC). We<br />

compute atmospheric profiles for surface temperatures ranging from 1000 to 2200 K,<br />

surface pressures of 10 and 100 bar, and surface gravities of 10 and 30 m/s 2 . Our<br />

calculations using extensive line lists bring a significant improvement over previous<br />

models, but still do not include cloud formation and aerosol opacities. We find that the<br />

post-giant-impact atmospheres are dominated by H2O and CO2, while the formation of<br />

CH4, and NH3 is quenched due to short dynamical timescales. Other important<br />

constituents are HF, HCl, NaCl, and SO2. Estimates including photochemistry and vertical<br />

mixing show atmospheric enhancements in sulfur-bearing species, particularly SO2, which<br />

produces strong spectral features. Estimated luminosities for post-impact planets, although<br />

lower than predicted by previous models, show that the hottest post-giant-impact planets<br />

will be detectable with the planned 30 m-class telescopes. Finally, we use the models to<br />

describe the cooling of a post-impact terrestrial planet and briefly investigate its time<br />

evolution. We find that the cooling timescale for post-giant impact Earths ranges between<br />

10 5 and 10 6 years, where the slower cooling is associated with the planet going through a<br />

runaway greenhouse stage.<br />

The impact of stellar winds on exoplanetary magnetospheres<br />

S.C. Marsden — University of Southern Queensland<br />

The habitable zone of an exoplanet is traditionally defined by the range<br />

of orbital distances where planetary surface temperatures are expected to<br />

allow for liquid water. However, given that stellar winds can erode<br />

planetary atmospheres even when a magnetosphere is present, it is proposed<br />

that considerations of planetary habitability include stellar wind<br />


pressure.The Bcool project is an international collaboration studying the<br />

magnetic fields of solar-type stars and whose results can be used for<br />

stellar wind studies. Using a simple wind model we show that an exoplanet<br />

like the present-day Earth would generally need to orbit outside the<br />

traditional habitable temperature zone of many solar-type stars to<br />

maintain the size of its magnetosphere. However, planets orbiting within<br />

the classical temperature habitable zone of solar-type stars should<br />

possess magnetospheres that although compressed, are likely to protect the<br />

planet's atmosphere and hence allow for the planet to be habitable.<br />

An aqua planet under strong solar forcing!<br />

Max Popp — Max Planck Institute for Meteorology<br />

A modified version of the general circulation model ECHAM6 is used to investigate the<br />

impact of increased total solar irradiance (TSI) on an aqua planet on a present-day Earthlike<br />

orbit. We find that the present-day Earth-like climate destabilizes for a TSI between<br />

1.06 and 1.08 times the present-day Earth value (S0). The aqua planet does not, however,<br />

go into a Runaway Greenhouse, but attains a new steady state with global-mean seasurface<br />

temperatures exceeding 335 K. This warm state is characterized by a low<br />

meridional temperature gradient, a weak meridional circulation without polar cells, a moist<br />

stratosphere and convection-dominated cloud formation. As the TSI is further increased,<br />

the planet remains in the same regime of warm steady states for TSIs of at least up to 1.2<br />

S0, because the cloud albedo increases as well, and balances the increased forcing. In<br />

these states, the volume mixing ratio of water vapor in the upper atmosphere may attain<br />

values as large as 0.015. This large mixing ratio exceeds the “Moist Greenhouse” limit<br />

(Kasting et al. 1993) and suggests that a planet in such a warm state would hence be<br />

subject to a rapid loss of water.<br />

Climate dynamics of a coupled Aquaplanet<br />

Josiane Salameh — Max Planck institute for Meteorology<br />

The idea behind an Aquaplanet, an idealized configuration of the current Earth with all the<br />

landmasses removed, is not recent. However, most of the research is conducted with<br />

stand-alone atmospheric models. Thus, the originality behind considering the coupled<br />

Aquaplanet setup, highlights the ocean's impact and allows us to directly interpret the<br />

fundamental processes and feedbacks between ocean and atmosphere without any land<br />

interference.<br />

As for the few coupled Aquaplanet studies lately conducted on General Circulation<br />

Models (GCM), they showed an extreme disparity regarding the final climate state. The<br />

range of states discovered lies between a warm climate qualified with a lack of sea-ice<br />

formation and a cold climate where sea-ice extend at the poles. Then, the existence of<br />

three equilibrium states was verified while integrating the same GCM from different<br />

random initial conditions.<br />

The climate of a coupled Aquaplanet remains an open question. Therefore, our task is to<br />

analyze the atmospheric-oceanic circulations of a coupled Aquaplanet while contributing to<br />

this discrepancy in previous results. The simulations are executed on “ICON”, based on an<br />

icosahedral triangular grid. Effects of rotation on Hadley cell's magnitude and extent, winds<br />

distribution and others were already theoretically discussed and numerically tested. In<br />

order to achieve a higher physical understanding of the Earth rotation rate and its effect on<br />


the global circulation features, especially the ocean, our future goal is to consider variable<br />

rotation rates in our coupled Aquaplanet setup.<br />

The Effect of Host Star Spectral Energy Distribution on Planetary Climate<br />

Aomawa Shields — University of Washington!<br />

Planetary climate can be affected by the interaction of the host star spectral energy<br />

distribution with the wavelength-dependent reflectivity of ice and snow. We have explored<br />

this effect with a hierarchy of models. Results from both one-dimensional radiative transfer<br />

and energy balance models and a three-dimensional general circulation model indicate<br />

that terrestrial planets orbiting stars with higher near-UV radiation exhibit a stronger icealbedo<br />

feedback. We found that ice extent is much greater on a planet orbiting an F-dwarf<br />

star than on a planet orbiting a G- or M-dwarf star at an equivalent flux distance, assuming<br />

fixed CO2 (present atmospheric level on Earth). The surface ice-albedo feedback effect<br />

becomes less important at the outer edge of the habitable zone for main-sequence stars,<br />

where the maintenance of surface liquid water requires high atmospheric CO2<br />

concentrations. We show that 3-10 bar of CO2 will entirely mask the climatic effect of ice<br />

and snow, leaving the outer limits of the habitable zone unaffected by the spectral<br />

dependence of water ice and snow albedo. However, less CO2 is needed to maintain open<br />

water for a planet orbiting an M-dwarf star than would be the case for hotter mainsequence<br />

stars. We also explore the sensitivity of climate hysteresis to spectral energy<br />

distribution, and examine how changes in planetary rotation rate and atmospheric<br />

composition affect our results.<br />

Marine Boundary Layer Clouds and their Interaction with the Large-scale<br />

Atmospheric Circulation: An Idealized-GCM Study<br />

Zhihong Tan! — California Institute of Technology / ETH Zurich<br />

Cloud feedback is one of the central uncertainties in climate modeling, and the short-wave<br />

radiative feedback of marine boundary layer (MBL) clouds is the most significant<br />

contributor to these uncertainties. We have incorporated a physically motivated eddy<br />

diffusivity/mass flux closure for convective turbulence coupled to a probabilistic cloud<br />

scheme in an idealized aquaplanet GCM to develop improved turbulence and cloud<br />

parameterizations and to study and constrain the physical mechanisms giving rise to cloud<br />

feedbacks. Subtropical MBL clouds are observed in simulations with the idealized GCM.<br />

We study their response to changes in the longwave optical depth and in the ocean heat<br />

flux to determine the sign and magnitude of MBL cloud feedback over a wide range of<br />

climates. We compare our results with previous modeling and observational studies, such<br />

as the reported dependence of the MBL cloud fractions on the lower troposphere stability.<br />

We discuss the mechanisms underlying the MBL cloud feedback and the degree to which<br />

they can be expected to be robust, as well as the interaction of MBL processes with the<br />

large-scale atmospheric circulation.<br />

Climate and Photochemistry of Known Potentially Habitable Exoplanets<br />

Feng Tian — Tsinghua University!<br />

Several potentially habitable planets are known today. What are the environments like on<br />

them Are they inhabited What are the potential signatures of life on them These are<br />

important scientific questions for the coming decade(s). Photochemistry is important for<br />


the climate on exoplanets by providing important species affecting radiation. On the other<br />

hand, climate may pose important constraints on atmospheric composition, based on<br />

which different schemes of photochemistry can perform. In this work we will discuss the<br />

interplays between exoplanet climate and atmospheric composition and photochemistry,<br />

focusing on potentially habitable exoplanets such as HD40307g and the GJ667C planets.<br />

Water loss from terrestrial planets with N2/CO2 atmospheres!<br />

Robin!Wordsworth! — University of Chicago!<br />

The initial volatile content delivered to terrestrial planets during accretion is most likely<br />

highly variable, with many planets receiving significantly more than Earth today possesses.<br />

Understanding how later processes such as photolysis-driven H2O loss affect planetary<br />

evolution is therefore vital to constraining the range of possibilities for both the early Solar<br />

System and for many recently discovered low-mass exoplanets. Here we discuss a range<br />

of calculations we have performed to study the dependence of water loss rates on a wide<br />

range of planetary parameters. We show through a combination of simple analysis and<br />

numerical climate models (1D and 3D) that the non-condensing atmospheric component<br />

plays a fundamental role in controlling water loss via regulation of the stratospheric cold<br />

trap. While CO2 can increase H2O transport to the high atmosphere over a small range of<br />

mixing ratios by increasing surface temperature, thermodynamic constraints and cooling of<br />

the middle/upper atmosphere act as a bottleneck on escape in other circumstances. The<br />

differing relationships of total stellar luminosity and stellar XUV with time for G-stars places<br />

strong limits on H2O loss rates for planets like Earth, although escape can reach higher<br />

values for planets with surface liquid water around M-stars. Because the carbon cycles of<br />

planets with ocean-covered surfaces are likely to be fundamentally different from that of<br />

Earth, our results have important implications for the likely surface and atmospheric<br />

characteristics of super-Earth exoplanets in the habitable zone.<br />

Oceanic Circulation of Tidally Locked Terrestrial Planets!<br />

Jun Yang — University of Chicago!<br />

A fully coupled oceanic-atmospheric general circulation model is modified to simulate the<br />

climate of tidally locked terrestrial planets. A central issue to be examined is to identify the<br />

determining factors of oceanic circulation and its associated heat transport in both zonal<br />

and meridional directions. In this study we will examine five planetary parameters: ocean<br />

depth, land-sea distribution, rotational period (equaling to orbital period), planetary radius,<br />

and gravity.<br />

All these simulations show an eastward current along the equator, transporting heat from<br />

dayside to nightside, and a meridional overturning circulation (MOC) in each hemisphere,<br />

transporting heat from tropics to high latitudes. The equatorial current is driven by the<br />

combined effect of surface wind streeses and Rossby waves in the ocean which transport<br />

eastward momentum from high latitudes to the equator. The MOC is driven by salinity and/<br />

or temperature contrasts between low and high latitudes. The salinity contrast results from<br />

sea ice formation at high latitudes which releases salt to the ocean, and from sea ice<br />

melting at low-latitude ice margins which decreases the salinity there. The strengths of the<br />

oceanic circulation and heat transport are signifcantly influenced by the five planetary<br />

parameters. We will further present how these parameters work.<br />


Towards the Minimum Inner Edge Distance of the Habitable Zone<br />

Andras Zsom — Massachusetts Institute of Technology!<br />

We explore the minimum distance from a host star where an exoplanet could potentially be<br />

habitable in order not to discard close-in rocky exoplanets for follow-up observations. We<br />

find that the inner edge of the Habitable Zone for hot desert worlds can be as close as<br />

0.38 AU around a solar-like star, if the greenhouse effect is reduced (low relative humidity),<br />

and the surface albedo is increased.<br />

We consider a wide range of atmospheric and planetary parameters such as surface<br />

pressure, relative humidity, CO2 mixing ratio, surface gravity, etc. We argue that if the<br />

dominant mode of precipitation is rain, the potentially habitable region is maximized on the<br />

dry planet. Based on this argument, we estimate that relative humidity levels of 1% or<br />

more can be sufficient to maintain a liquid water cycle. If the surface pressure is too low<br />

(~0.1 bar), the water loss timescale of the planet is too short to support life. If the surface<br />

pressure is too high (~100 bars), we show using atmospheric circulation arguments, that<br />

the day-night side temperature difference on slow rotators is too small to enable an active<br />

water cycle. Intermediate surface pressures (~1-10 bars) can provide suitable conditions<br />

for a water cycle independent of the planetary rotation period. We additionally find that the<br />

water loss timescale is influenced by the atmospheric CO2 level, because it indirectly<br />

influences the stratospheric water mixing ratio.<br />

We also show that the expected transmission spectra of hot desert worlds are similar to<br />

an Earth-like planet. Therefore, an instrument designed to identify biosignature gases in an<br />

Earth-like atmosphere can also identify similarly abundant gases in the atmospheres of dry<br />

planets.<br />


The Atmospheres of GJ1214b and GJ436b: A Comprehensive Retrieval Study Based<br />

on Unprecedented Data from Two Large-Scale HST Campaigns<br />

Bjørn! Benneke — California Institute of Technology!<br />

In this talk, we present the scientific interpretation for two unprecedented HST WFC3<br />

campaigns to observe the transmission spectra of the warm exo-Neptune GJ436b and the<br />

warm super-Earth GJ1214b. We report statistically robust constraints on the atmospheric<br />

gas composition as well as the cloud properties such as cloud composition, cloud top<br />

altitude, and particle size distribution.<br />

Our main result for GJ1214b is that the observations require the presence of high-altitude<br />

clouds at high significance, independent of the atmospheric composition and mean<br />

molecular mass. We investigate the full range of physically plausible cloud properties that<br />

may explain the observations. For GJ436b we find that high-altitude clouds could similarly<br />

explain the observed flat transmission spectrum, suggesting that a similar cloud formation<br />

mechanism may be at play in the two planets. Alternatively, we suggest the intriguing<br />

possibility that GJ436b hosts an atmosphere which is strongly metal-enriched compared to<br />

the gas and ice giants in our solar system.<br />

The atmospheric constraints are obtained using a novel self-consistent inversion<br />

framework that combines the observational data with our prior understanding of<br />

atmospheric physics and chemistry in a statistically robust manner. The new framework<br />

makes full use of all information at hand and identifies the full range of scenarios that are<br />

both physically plausible and in agreement with the data. We describe the merits of this<br />


new inversion framework for the interpretation of atmospheric spectra of both exoplanets<br />

and Solar System planets.<br />

How Do Mini-Neptunes Migrate<br />

Zachory Berta-Thompson — Massachusetts Institute of Technology!<br />

To understand an exoplanet, we need to know how it got where it is today. Because it<br />

transits a very nearby, very small star, the exoplanet GJ1214b is a useful laboratory for<br />

studying the physics of planets near the fuzzy boundary between super-Earths and sub-<br />

Neptunes. However, little is known about how GJ1214b migrated to its current close-in<br />

orbit. Was it scattered wildly inward and later tidally circularized, as many hot Jupiters<br />

appear to have been Or was it coaxed in smoothly and gently, as seems to be the case<br />

for the compact, coplanar, small-planet systems uncovered by Kepler To address this<br />

conundrum, we search for and analyze recurrent starspot occultations in closely-spaced<br />

transit light curves of GJ1214b taken with the Magellan, Gemini, and Hubble telescopes.<br />

We use these spot occultations to constrain the relative orientation of the planet’s orbit to<br />

the host star’s spin axis, which can be used to distinguish among possible scenarios for<br />

the migration history of the planet. This analysis bears not only on the one particularly<br />

useful GJ1214b system, but also on the processes that may shape many of the abundant<br />

close-in, low-mass, low-density exoplanets that populate our Galaxy.<br />

Water Cycling between Ocean and Mantle: Super-Earths need not be Waterworlds<br />

Nicolas Cowan — Northwestern University<br />

Large terrestrial planets are expected to have muted topography and deep oceans,<br />

implying they should be entirely covered in water, so-called waterworlds. Quantitatively, a<br />

planet ten times the mass of Earth is not expected to have exposed continents unless it<br />

has a water mass fraction less than 3x10^-5, roughly ten times drier than Earth.<br />

Waterworld climate is predicted to be less stable than that of planets with exposed<br />

continents. Water is partitioned, however, between a surface reservoir, the ocean, and an<br />

interior reservoir, the mantle. Plate tectonics transports water between these reservoirs on<br />

geological timescales. Degassing of melt at mid-ocean ridges and serpentinization of<br />

oceanic crust are mediated by sea-floor pressure, providing a stabilizing feedback on longterm<br />

ocean volume. Motivated by Earth's approximately steady-state deep water cycle, we<br />

develop a two-box model of the hydrosphere and derive steady-state solutions to the<br />

water-partitioning on terrestrial planets. Since hydrostatic pressure is proportional to<br />

gravity, super-Earths with a deep water cycle will tend to store most of their water in the<br />

mantle. We conclude that tectonically active terrestrial planets with H2O mass fractions<br />

less than 3x10 -3 will have both oceans and exposed continents.<br />

Transiting planets around nearby M dwarfs: updates from the APACHE Project<br />

Mario! Damasso — University of Padova<br />

Across the Alps, just few hundreds km from Davos as the crow flies, a search for<br />

transiting, small-size planets orbiting M dwarfs is in progress since July 2012: the APACHE<br />

Project (A PAthway toward the Characterization of Habitable Earths). APACHE is a survey<br />

“made in Italy” carried out as a collaboration between the Astronomical Observatory of the<br />

Autonomous Region of Aosta Valley and INAF-Torino Astrophysical Observatory, which will<br />

last five years and collect a huge database of photometric data. It uses five identical,<br />


automatic 400mm telescopes to observe thousands of carefully selected nearby red<br />

dwarfs. Nearby, bright M dwarfs are optimal targets as host stars for transiting planets<br />

which can be extensively followed up to analyze their atmospheres, as demonstrated by<br />

the case of the extrasolar planet GJ 1214b.<br />

We present the results of the first observing season for several dozens of cool stars,<br />

including detailed simulations aimed at estimating the sensitivity of APACHE to transiting<br />

planets of different sizes. Moreover, we will discuss the results obtained for a sample of<br />

stars which have been also monitored spectroscopically with HARPS-N@TNG in the<br />

framework of the Large National Program GAPS.<br />

In the spotlight: small planets transiting bright stars!<br />

Diana!Dragomir — UC Santa Barbara/Las Cumbres Observatory Global Telescope<br />

The Kepler transit survey has resulted in the discovery of more than a dozen super-Earth<br />

planets. Super-Earths are of particular interest in exoplanet research because they<br />

constitute a class of objects which are not represented in our Solar System, though<br />

statistics from Kepler and radial velocity surveys suggest they are relatively common<br />

around other stars. Moreover, these planets can theoretically have a wide range of<br />

densities and therefore compositions which we have only very recently begun to explore<br />

observationally. While studies of super-Earth hosting systems based on Kepler photometry<br />

have contributed significantly to our understanding of these objects, follow-up observations<br />

of these planets' atmospheres prove difficult or impossible to carry out with existing<br />

instruments due to the faintness of most of the stars in the Kepler field. In order to better<br />

understand the nature of this class of planets, we must focus on super-Earths transiting<br />

bright stars (allowing for higher-precision observations) and/or small stars (leading to<br />

deeper transits more amenable to transmission spectroscopy measurements). I will focus<br />

on 55 Cnc e and HD 97658b, the two currently known transiting super-Earths which fall in<br />

the former category. The 55 Cnc system has been observed with the MOST space<br />

telescope for a total of 70 days over a period of three years. I will present results based on<br />

the analysis of these data, including constraints on the secondary eclipse (and hence the<br />

albedo) of 55 Cnc e, and discuss implications for the planet's atmospheric composition. I<br />

will also present MOST photometry of HD 97658b and describe the current state of<br />

knowledge of this low-density super-Earth's structure and composition, including a report<br />

on our efforts to probe its atmosphere with the HST and Spitzer.<br />

Atmospheric Composition of the ExoNeptune HAT-P-11b!<br />

Jonathan D.! Fraine!— University of Maryland<br />

We present new observations of the transiting exo-Neptune HAT-P-11b from a joint HST<br />

and warm Spitzer program to measure the transmission spectrum of its thick atmosphere.<br />

Our data cover a wide span of wavelength space, including warm Spitzer IRAC 3.6 & 4.5<br />

micron photometry and Hubble WFC3 1.1 - 1.7 micron spectroscopy from our<br />

observations, as well as Kepler's optical photometry centered at 632nm. Our WFC3<br />

spectroscopic observations are among the first using HST's new spatial scanning mode for<br />

optimised signal-to-noise spectroscopy. In addition, HAT-P-11 is one of the most active<br />

planet-hosting stars; observations of HAT-P-11b's atmosphere therefore allow us to shed<br />

light on the role that stellar activity may play in shaping the atmospheric chemistry of<br />

Neptune-sized planets. We use the Kepler photometry to model and remove the effects of<br />

the stellar activity during and surrounding our warm Spitzer transit observations. Our<br />


combined observations provide constraints on the existence of clouds or hazes and the<br />

atmospheric chemistry at the day-night terminator.<br />

Neptunes in the Noise: Improved Precision in Exoplanet Transit Detection!<br />

Aimée E. Hall — Institute of Astronomy, University of Cambridge!<br />

SuperWASP is an established, highly successful ground-based survey that has already<br />

discovered over 80 exoplanets around bright stars. It is only with wide-field surveys such<br />

as this that we can find planets around the brightest stars, which are best suited for<br />

advancing our knowledge of exoplanetary atmospheres. However, complex instrumental<br />

systematics have so far limited SuperWASP to primarily finding hot Jupiters around stars<br />

fainter than 10th magnitude. By quantifying and accounting for these systematics up front,<br />

rather than in the post-processing stage, the photometric noise can be significantly<br />

reduced.<br />

In this paper, we present our methods and discuss preliminary results from our reanalysis.<br />

We show that the improved processing will enable us to find smaller planets<br />

around even brighter stars than was previously possible in the SuperWASP data. Such<br />

planets could prove invaluable to the community as they would potentially become ideal<br />

targets for the studies of exoplanet atmospheres.<br />

Water content and hydrogen-rich atmoshperes of sub-/super-Earths orbiting cool<br />

stars<br />

Yasunori Hori — National Astronomical Observatory of Japan!<br />

Over the past five years, close-in low-mass exoplanets orbiting cool stars has increased in<br />

number rapidly. Recently, transmission spectra in a planetary atmosphere during a primary<br />

eclipse have enabled us to explore the atmospheric compositions of super-Earths. Habitat<br />

environment and formation histories of close-in planets are closely related to volatile<br />

inventories in their atmospheres such as water and hydrogen. We have examined the<br />

water content and the amount of hydrogen-rich atmospheres of sub-/super-Earths around<br />

cool stars, performing 1,000 Monte Carlo simulations of planet formation. We have found<br />

that super-Earths with 1-30 Earth-mass are likely to possess more than 20-30wt% water<br />

mantles surrounded by thick H2-rich blankets: 0.1-20wt% H-He atmospheres for 1-10<br />

Earth-mass planets inside 0.1AU, such as GJ 1214b, and more than 50wt% for larger<br />

planets inside 1AU like GJ 436b. We have also shown that dry/wet sub-Earths with 0.1-1<br />

Earth-mass inside 1AU end in naked ones with less than 1wt% H-He atmospheres. Our<br />

results predict that sub-Earths in a habitable zone are wet but have almost no primitive<br />

atmosphere, while super-Earths near/in the zone, for example, GJ 581d, GJ 667Cc, and<br />

GJ 163c, contain abundant water and sufficient H2-rich atmospheres. Moderately-wet<br />

planets with 0.001-1wt% water similar to the Earth, i.e., land planets, are either a small<br />

fraction of sub-Earths near the inner edge or non-migrating planets near 1AU. In any case,<br />

water worlds of sub-/super-Earths in a multiple-planet system are common around cool<br />

stars.<br />

Helium-Dominated Atmosphere on Neptune-Sized Exoplanet GJ 436b<br />

Renyu Hu — California Institute of Technology!<br />

The composition of the atmosphere on exoplanet GJ 436b, the most characterized<br />

Neptune-sized exoplanet to date, has been a long-standing puzzle. The dayside emission<br />


of the planet shows that its atmosphere is poor in methane and rich in carbon monoxide<br />

and carbon dioxide, yet both equilibrium chemistry and disequilibrium chemistry models<br />

predict most carbon to be in the form of methane for the temperature of the planet. This<br />

contradiction is further intensified by the planet's large radius and low mean density, which<br />

requires the planet to have an extensive gas envelope. Here we provide an explanation for<br />

both the planet's emission spectrum and the planet\s radius. We propose that the<br />

atmosphere of GJ 436b is mainly composed of helium. We have used a recently<br />

established photochemistry-thermochemistry kinetic-transport model to compute the<br />

molecular composition of the thick atmosphere on GJ 436b, with the helium versus<br />

hydrogen ratio and the carbon and oxygen abundances as free parameters. The<br />

temperature of the atmosphere is self-consistently computed using grey-atmosphere<br />

approximation from the composition governed by disequilibrium chemistry. We find that a<br />

helium-dominated atmosphere with hydrogen elemental abundance less than 3% by<br />

number will have carbon dioxide and carbon monoxide as the main forms of carbon and<br />

little methane, and thus lead to spectral features consistent with observations. Such an<br />

atmosphere has mean molecular mass of ~4, only 2 times greater than that of a hydrogendominated<br />

atmosphere, and therefore the helium-dominated atmosphere can be extended<br />

enough to meet the mass-radius constraint of the planet. To form such a helium-dominated<br />

atmosphere on a Neptune-sized exoplanet, we suggest that efficient hydrodynamic<br />

atmospheric loss should have occurred in the early history of the planet. Hydrodynamic<br />

escape has removed most of the hydrogen from gas accretion, and also removed some of<br />

the helium, which resulted in the enrichment of helium in the planet's gas envelope. If this<br />

mechanism is correct, one would expect helium-dominated atmospheres to be common on<br />

Neptune and sub-Neptune sized exoplanets around M dwarfs.<br />

Exploring the Relationship Between Exoplanet Mass and Atmospheric<br />

Metallicity!<br />

Joshua Kammer — California Institute of Technology!<br />

Studies of hydrogen-dominated planetary atmospheres in our solar system have shown<br />

that as core mass fraction increases, so does atmospheric metallicity. This hypothesis<br />

holds true for Uranus and Neptune, as these planets have atmospheres more enriched<br />

relative to solar metallicity (30-40x) as compared to Jupiter (3x). Though these planets'<br />

bulk densities are comparable to many detected exoplanets in the same size range, it<br />

remains an open question whether the metallicities of exoplanet atmospheres also follow a<br />

similar trend. One way to explore the correlation between planet mass and atmospheric<br />

metallicity is by characterization of secondary eclipse emission spectra. For cooler<br />

exoplanets (T < 1000 K) atmospheric models predict that carbon chemistry should be<br />

dominated by CH4 rather than CO for an atmosphere of solar metallicity. Increasing the<br />

atmospheric metallicity will suppress the amount of methane and enhance CO, as<br />

proposed by Moses et al. (2013) to explain GJ 436b's unusually low methane-to-CO ratio.<br />

Here we present results and analysis of Spitzer 3.6 and 4.5 μm secondary eclipse<br />

observations of seven exoplanets with masses ranging from sub-Neptune to super-Jupiter<br />

in size. Although they do not provide unique constraints on all the relative abundances of<br />

water, methane, CO, and CO2, these measurements can reveal empirical trends in CH4-to-<br />

CO ratios for cooler exoplanets in this size range, and test the correlation between<br />

exoplanet mass and atmospheric metallicity.<br />


Constraining the degeneracy of Super-Earth phase curve measurements<br />

Daniel D.B. Koll — University of Chicago!<br />

Thermal phase curve measurements of transiting exoplanets offer direct insight into how<br />

efficiently their atmospheres redistribute heat. These measurements already indicate<br />

distinct atmospheric circulation regimes on hot Jupiters, and stand to be a prime tool for<br />

remotely characterizing Super-Earth atmospheres. However, for Super-Earths the<br />

efficiency of atmospheric energy transport depends on a large number of difficult-toconstrain<br />

parameters (atmospheric composition & mass, presence/absence of condensible<br />

gases, surface type etc.). Assuming imperfect knowledge of these parameters, how<br />

degenerate are phase curve measurements Can we use phase curve measurements to<br />

robustly distinguish between different atmospheric scenarios, or do we need additional<br />

information from, e.g., transit spectroscopy<br />

To answer this question, it is necessary to comprehensively map out how the<br />

atmospheric energy transport depends on a large number of atmospheric parameters. To<br />

make the problem computationally tractable we non-dimensionalize the primitive equations<br />

and equations of grey-gas radiative transfer and find a reduced set of non-dimensional<br />

numbers that govern the atmospheric dynamics. We present simulations with an idealized<br />

dry global climate model (GCM) to demonstrate the utility of this approach. We also<br />

present results on how the atmospheric energy transport varies over the phase space<br />

spanned by these non-dimensional numbers, focusing on the relative roles of dynamics,<br />

radiation and uncertain model parameterizations.<br />

Transmission Spectroscopy of the Super-Earth Archetype GJ 1214b!<br />

Laura! Kreidberg — University of Chicago!<br />

Super-Earths, exoplanets intermediate in size between Earth and Neptune, are among the<br />

most prevalent planets in the Galaxy. Revealing the composition and formation histories<br />

of these common objects requires atmospheric characterization. I will present the results<br />

of an intensive observational campaign to study the atmosphere of the super-Earth<br />

archetype GJ 1214b. We observed 15 transits of the planet with the Hubble Space<br />

Telescope in the near-infrared, yielding the most precise exoplanet transmission spectrum<br />

measurement ever obtained in this wavelength range. Our measurements definitively<br />

distinguish between clear, high mean molecular weight atmospheric models and models<br />

with high-altitude clouds. I will also discuss preliminary results of a Gemini program to<br />

measure the transmission spectrum in the blue optical.<br />

Understanding Kepler's Super-Earths and Sub-Neptunes: Insights from Thermal<br />

Evolution and Photo-Evaporation!<br />

Eric Lopez — UC Santa Cruz<br />

NASA's Kepler mission has discovered a large new population of super-Earth and sub-<br />

Neptune sized planets. Although we have no analogous planet in our own solar system,<br />

such planets are incredibly common. Understanding the nature and formation of systems<br />

of these planets is one of the key challenges for theories of planet formation. We use<br />

models of thermal evolution and photo-evaporation to constrain the structure, composition,<br />

and evolution of low-mass planets. Over time Neptune-like planets with large H/He<br />

envelopes can be transformed into rocky super-Earths. We show that differences in mass<br />

loss history provide a natural explanation for many features of the Kepler multi-planet<br />

systems, such as large density contrast between Kepler-36b and Kepler-36c. For the<br />


oader population of Kepler planets, we find that there is a threshold in bulk planet<br />

density, mass, and incident flux above which no low-mass transiting planets have been<br />

observed. We suggest that this threshold is due to XUV-driven photo-evaporation and<br />

show that it is well reproduced by our evolution models.<br />

Chemical Characterization of Super-Earths: Interiors, Atmospheres, and Formation<br />

Conditions<br />

Nikku! Madhusudhan — Yale University<br />

Recent advances in exoplanetary science are leading to unprecedented observations of<br />

super-Earths. The observed masses, radii, and temperatures of super-Earths provide<br />

constraints on their interior structures, geophysical conditions, as well as their atmospheric<br />

compositions. Some of the most recently detected super-Earths span a wide gamut of<br />

possible compositions, from super-Mercuries and lava planets to water worlds with thick<br />

volatile envelopes. In this work, we report joint constraints on the interior and atmospheric<br />

compositions of several super-Earths and discuss their possible formation scenarios using<br />

new and comprehensive hybrid models of their interiors, non-gray atmospheres, and<br />

formation conditions. Our model constraints are based on the masses and visible radii, as<br />

well as the latest infrared measurements of transmission and emission spectrophotometry<br />

where available, in addition to revised estimates of the stellar parameters. We will present<br />

a comparative analysis of several transiting super-Earths currently known and will discuss<br />

in detail two super-Earths (GJ 1214b and 55 Cancri e) which have atmospheric data<br />

available and which represent two distinct end members in the thermo-chemical phase<br />

space of super-Earth conditions. We will also discuss the implications of our results for the<br />

diversity of geochemical and geophysical conditions on super-Earths. We will conclude<br />

with comments on new observational, theoretical, and experimental efforts that are critical<br />

to detailed characterization of super-Earths.<br />

Multi-Color Simultaneous Transit Photometry of Planets around Cool Host Stars<br />

Norio Narita — National Astronomical Observatory of Japan<br />

Transmission spectroscopy is a powerful method to investigate planetary atmospheres for<br />

transiting exoplanets. For ground-based large (6-10 m class) telescopes, multi-object<br />

spectroscopy and high dispersion spectroscopy have shown successful results for this<br />

purpose. For smaller (1-2 m class) telescopes, multi-color simultaneous transit photometry<br />

provides an alternative and efficient way for transmission spectroscopy. In this talk, we<br />

focus on such multi-color simultaneous transit photometry for planets around cool host<br />

stars, including GJ1214, GJ3470, and WASP-80. We present some observational results<br />

taken in 2011 and 2012 seasons (e.g., Narita et al. 2013a, Narita et al. 2013b, Fukui et al.<br />

2013) and preliminary results for data taken in 2013 season.<br />

Characterizing the Demographics of Exoplanet Bulk Compositions<br />

Leslie Rogers — California Institute of Technology<br />

The Kepler Mission has discovered thousands of sub-Saturn-sized transiting planet<br />

candidates. Using planet interior structure models, we constrain the bulk compositions of<br />

the more than 50 known sub-Saturn-sized transiting planets with measured masses. Our<br />

model considers fully differentiated planets comprised of up to four layers: an iron core, a<br />

silicate mantle, a water mantle, and a gas envelope. We calculate the planet interior<br />


structure by integrating the coupled differential equations describing an evolving selfgravitating<br />

body, employing modern equations of state for the iron, silicates, water, and<br />

gas. For any individual planet, a wide range of compositions is consistent with the<br />

measured mass and radius. We consider the planets as an ensemble, and discuss how<br />

thermal evolution, mass loss, and observational biases sculpt the observed planet massradius-insolation<br />

distribution. Understanding these effects is crucial for constraining the<br />

demographics of small planet bulk compositions and for extracting signatures of the planet<br />

formation process from the accumulating census of transiting planets with dynamical<br />

confirmation.<br />

Ground-based search for the transit of Alpha Cen Bb<br />

Aurelien Wyttenbach — Geneva Observatory<br />

In late 2012, a planet with a minimum mass of 1.13 earth mass may have been detected<br />

around Alpha Cen B with the HARPS spectrograph. With a 3.2 days orbit, the planet has a<br />

10% transit probability. However, with an expected transit depth of ~100 ppm, searching<br />

for the transit is challenging, especially from the ground because of correlated noise in the<br />

light curves. The extreme brightness of Alpha Cen B, and the close separation from Alpha<br />

Cen A (4") complicate the task further. We have developed and tested a method designed<br />

to beat down correlated noise, while coping with the brightness and duplicity of the Alpha<br />

Cen system, using high-resolution spectroscopy. Here, we present the first light curve of<br />

Alpha Cen B obtained using this method during one night of observations with UVES at<br />

the VLT.<br />


Spectrophotometry with SOFIA: First results!<br />

Daniel!Angerhausen — Rensselaer Polytechnic Institute<br />

Over the past decade the transit method (measuring the small, wavelength-dependent<br />

variation in flux as an exoplanet passes in front of or behind its parent star) has produced<br />

a number of exciting characterization results. The NASA/DLR Stratospheric Observatory<br />

for Infrared Astronomy (SOFIA), a 2.5-meter infrared telescope on board a Boeing 747-SP,<br />

has a specific and unique phase space for these extremely precise time-domain<br />

spectrophotometric observations at IR wavelengths: It operates in the right wavelength<br />

regime, where the planet's black-body temperature peaks and contrast ratios between star<br />

and planet improve. The airborne observatory is able to avoid most of the perturbing<br />

variation of atmospheric trace gases that produce the dominant source of noise for<br />

ground-based observations in the near-infrared. These telluric molecules are also the<br />

species of interest in the exo-atmospheres. The SOFIA telescope is operating at much<br />

lower temperatures (~240 K) than ground-based telescopes (~273 K). Therefore thermal<br />

background contributions, the dominant noise source for transit observations at<br />

wavelengths longer than 3 micron, will be significantly reduced. The mobile platform<br />

SOFIA can observe time-critical events, such as the rare transits of long-period planets,<br />

under optimized conditions. After the end of Spitzer and until the start of the JWST<br />

mission, SOFIA will be the only observatory capable of NIR spectrophotometry of<br />

exoplanet atmospheres beyond 1.7 micron (the upper limit for HST after the last upgrade)<br />


at an altitude where the impact of variable telluric absorption is small enough for high<br />

precision observations of the same molecules also present in exoplanet atmospheres.<br />

Here we present SOFIA's unique advantages in comparison to ground- and space-based<br />

observatories in this field of research and present the very first spectrophotometric<br />

exoplanet observations that were or will be conducted in SOFIA’s cycles 1 and 2.<br />

Characterisation of Exoplanets using Polarization!<br />

Jeremy Bailey — University of New South Wales!<br />

Light reflected from the atmospheres of extrasolar planets will be polarized, and the<br />

detection and measurement of that polarization provides a means of characterising the<br />

atmospheres that provides complementary information to that from spectroscopy. At<br />

UNSW we are building a new instrument with the aim of measuring polarization in the<br />

combined light of a star and hot Jupiter planet, and thus detecting the polarization of the<br />

planet. We have also incorporated polarization capability into our atmospheric modelling<br />

code VSTAR. Polarization is particularly sensitive to the presence of atmospheric clouds<br />

and hazes. I will describe our current progress on these developments, and discuss the<br />

potential of such techniques for the study of exoplanet atmospheres.<br />

Polarimetric detection and characterization of hot Jupiters!<br />

Andrei! Berdyugin — FINCA, University of Turku, Finland<br />

The light scattered in planetary atmospheres is linearly polarized perpendicular to the<br />

scattering plane. In general, when the planet rotates around the parent star, the scattering<br />

angle changes and the Stokes parameters Q and U of linear polarization vary. If the orbit is<br />

close to circular, two peaks per orbital period are observed. The observed polarization<br />

variability exhibits therefore the orbital period of the planet and reveals the inclination,<br />

eccentricity, and orientation of the orbit. Due to proximity to the star, hot giant planets with<br />

short orbital periods ("hot Jupiters") may develop extended peculiar atmospheres and<br />

halos which effectively scatter the light in the blue spectral region. This can give rise to a<br />

degree of polarization detectable with the currently existing modern polarimeters.<br />

Parameters of this polarization, e.g., wavelength dependence, are defined by physical<br />

conditions in the upper layers of the planetary atmosphere. Thus, polarimetry of hot "blue<br />

Jupiters" in combination with other methods of observations may be used to draw<br />

conclusions on properties of their atmospheres.<br />

Here we present new polarimetric observations of several hot Jupiters, both transiting<br />

and non-transiting, in three bands: blue, green, and red. These data were obtained with<br />

two instruments: (1) our new Double Imaging Polarimeter (DIPol-2) at the 60cm KVA<br />

telescope on La Palma, routinely providing polarimetric accuracy of 10 -5 , and (2) the FORS<br />

polarimeter at the VLT, ESO, with the maximum accuracy of 10 -4 . We analyze these data<br />

using our model calculations and infer planet orbit parameters and atmosphere reflectivity.<br />

We compare our results with measurements of the secondary eclipses of hot Jupiters.<br />

Detecting water in hot Jupiter atmospheres with high-resolution ground-based<br />

spectroscopy!<br />

Jayne!Birkby — Leiden Observatory<br />

The robust determination of the chemical make-up of exoplanet atmospheres is crucial to<br />

understanding their structure, formation, and evolution, particularly in the case of the major<br />


carbon- and oxygen-bearing species. We present ground-based high-resolution spectra<br />

from CRIRES/VLT at 3.2 microns of several transiting and non-transiting hot Jupiter<br />

atmospheres (51 Peg b, Tau Boo b, and HD 209458 b), in which we have searched for the<br />

radial velocity signature of water, methane and carbon dioxide molecules in the planetary<br />

atmospheres. We compare the results of our search with the detections of CO already<br />

reported in these hot Jupiter atmospheres, and discuss their temperature-pressure profiles<br />

and relative abundance ratios. Preliminary results indicate a significant abundance of<br />

water in 51 Peg b, consistent with tentative reports of water at 2.3 microns.<br />

Observation of Magnesium : A new Probe of Exoplanets' Thermospheres and<br />

Exopheres!<br />

Vincent Bourrier — Institut d'Astrophysique de Paris<br />

Transit observations of HD209458b in the UV revealed signatures of neutral magnesium<br />

escaping the planet upper atmosphere. The absorption detected in the MgI line arises from<br />

the transition region between the thermosphere and the exosphere, and provides<br />

unprecedented information on the physical conditions at the altitude where atmospheric<br />

escape takes place. These observations have been interpreted using a 3D particle model<br />

coupled with an analytical modeling of the atmosphere below the exobase. Thus we<br />

estimated the planetary wind velocity and the exobase altitude, and also obtained an new<br />

estimate of the atmospheric escape rate. More generally, we show that magnesium<br />

absorption lines provide a powerful tool to study the upper part of exoplanets'<br />

atmospheres. We identified a dozen of exoplanets with host stars bright enough for their<br />

atmosphere to be observed using the magnesium lines.<br />

Probing the atmospheres of non-transiting exoplanets: CO and H2O absorbtion in<br />

HD179949b!<br />

Matteo Brogi! — Leiden Observatory<br />

In recent years, ground-based high-resolution spectroscopy has become a powerful<br />

method for studying exoplanet atmospheres. It is capable to robustly identify molecular<br />

species via line matching, and to detect the radial velocity of the planet itself. Moreover, by<br />

targeting the planet thermal emission directly, it does not require the planet to transit.<br />

Thanks to this method, the mass and orbital inclination of non-transiting planets can be<br />

determined and their atmospheric composition studied.<br />

I will present our latest K-band observations of HD179949b with CRIRES at R=100,000.<br />

We detect an absorption signal from water vapour and carbon monoxide at SNR=6.5,<br />

meaning that the portion of the planet’s atmosphere probed by these observations does<br />

not have an inversion layer. The derived mass and orbital inclination for the planet are<br />

(0.98+/-0.04) Jupiter masses and (68+/-4) degrees respectively.<br />

Except for young, self-luminous directly-imaged planets, only high-resolution<br />

spectroscopy currently allows the atmospheric characterization of non transiting planets.<br />

With the next generation of ELTs and this technique, a complete census of this class of<br />

bodies will be possible, revealing for the first time their properties and actual mass<br />

distribution.<br />


Spectroscopic observations of the hot-Jupiter HD 189733b with HST WFC3<br />

Nicolas Crouzet — Space Telescope Science Institute<br />

Spectroscopic observations of exoplanets are crucial to infer the composition and<br />

properties of their atmosphere. In particular, identifying molecular features and measuring<br />

their amplitude constrain the presence of and the effect of clouds, which are thought to<br />

play a major role in the atmosphere of hot-Jupiters. After a controversy on the reliability of<br />

NICMOS results, the Wide Field Camera 3 (WFC3) on board the Hubble Space Telescope<br />

now delivers hot-Jupiter spectra with much higher fidelity than HST NICMOS had in the<br />

past. We observed the well studied hot-Jupiter HD 189733b with WFC3 in the bandpass<br />

1.1 to 1.7 microns using the newly implemented spatial scanning mode, which largely<br />

increases the number of collected photons compared to the staring mode. Also, the<br />

spatially-scanned WFC3 data produce satisfactory results with a very straight-forward<br />

analysis, a welcome change from the old technique of staring-mode observations,<br />

especially those obtained with HST NICMOS (Crouzet et al. 2012). We will discuss the<br />

amplitude of absorption seen in the transmission spectrum and the inferred atmospheric<br />

composition for HD 189733b, and compare them with recent results by Deming et al.<br />

(2013) for the exoplanets HD 209458b and XO-1b using similar WFC3 data. Our data<br />

reinforces the idea that molecular features of hot Jupiters may be attenuated by the<br />

presence of clouds or haze. We derive the planetary emission spectrum using the same<br />

technique with observations made at secondary eclipse.<br />

A Closer Look at Correlated-Noise Measuring Techniques for Exoplanet Light<br />

Curves<br />

Patricio Cubillos — University of Central Florida<br />

Among the many exoplanet light-curve fits analyzed to date, it is not unusual to detect<br />

some degree of time correlation in the residuals (also known as correlated or red noise).<br />

An incorrect assessment of correlated noise can lead to under- or overestimating the<br />

uncertainties on the planet's physical parameters, giving more or less significance to the<br />

results than they should have. While the sources of correlated noise are not always<br />

known (e.g., from an inaccurate systematics treatment or some unaccounted astrophysical<br />

effect), there are methods that aim to assess the degree of correlated noise, like the RMSvs.-bin<br />

size plot, prayer beads, and wavelet-based likelihood fitting. Yet, there are no indepth<br />

statistical studies in the literature for some of the techniques currently used.<br />

We subjected these correlated-noise assessment techniques to basic tests on synthetic<br />

data sets to characterize their features and limitations.<br />

Initial results indicate, for example, that sometimes the RMS-vs.-bin size plot has large<br />

artifacts when the bin size is similar to the observation duration. Further, prayer beads<br />

rarely indicate the right level of correction for correlated noise. We have applied these<br />

techniques to several Spitzer secondary-eclipse hot-Jupiter light curves and discuss their<br />

implications.<br />

New possibilities for exoplanet observations at high spectral resolution<br />

Remco de Kok — SRON<br />

In the last few years there have been several detections of molecules in hot-Jupiter<br />

atmospheres using observations at very high spectral resolution (R=100,000), most<br />

notably using CRIRES on the VLT. These observations have the great advantage that they<br />

allow unambiguous detection of specific molecules. On the other hand, determining<br />


abundances of molecules in the atmosphere has not yet been possible using only highresolution<br />

observation due to degeneracies. We will discuss what other high-resolution<br />

measurements can be performed with current instruments to obtain a better understanding<br />

of the chemistry and dynamics of hot-Jupiter atmospheres. We will present results from<br />

our sensitivity analysis of simulated CRIRES observations, showing at what wavelengths<br />

particular molecules are best detected. We will also discuss whether molecules can be<br />

detected from high-resolution thermal radiation from the night-side. We find that for some<br />

planets the night-side might even yield a larger signal than the day-side.<br />

2D mapping of the eccentric exoplanet HAT-P-2b!<br />

Julien!de Wit — Massachusetts Institute of Technology<br />

The class of close-in gas giant planets known as hot Jupiters provides an exceptional<br />

insight into atmospheric circulation, as these planets are expected to be both highly<br />

irradiated and in either synchronous or pseudo-synchronous orbits depending on their<br />

orbital eccentricity. We can probe atmospheric circulation through phase curve<br />

measurements, which tell us about their brightness as a function of longitude. Recently, a<br />

new observational tool, “eclipse mapping”, has been developed enabling the creation of<br />

maps that are resolved in both longitude and latitude, unlike phase curves. To date, only<br />

one planet (HD 189733b) has been successfully mapped using this technique. Here, we<br />

present the first two-dimensional maps of the eccentric exoplanet HAT-P-2b in the Spitzer<br />

4.5 micron bandpass. This map is derived from fourteen new secondary eclipses observed<br />

in the 4.5 micron band.<br />

The high eccentricity of HAT-P-2b leads to fundamental differences between its<br />

atmospheric circulation and that of HD189733b. A high eccentricity prevents tidal locking<br />

and implies time-variable stellar heating, hence time-variable forcing. HAT-P-2b is eclipsed<br />

post-periastron, hence we use eclipse mapping to gain insights into how its atmosphere<br />

responds to transient heating. In particular, HAT-P- 2b’s map will yield constraints on its<br />

radiative and advective time-scales and probe the spatial extent of its dayside thermal<br />

inversion. We will discuss the implication of our findings in the context of atmospheric<br />

circulation models that can be applied to a wide range of planets.<br />

Mapping Clouds in Exoplanet Atmospheres<br />

Brice-Olivier Demory — Massachusetts Institute of Technology<br />

Clouds and hazes are ubiquitous in the solar system's giant planet and brown-dwarf<br />

atmospheres. It has been long suggested that clouds would also play a strong role in<br />

shaping the spectra of exoplanets in general and hot Jupiters in particular. Recently,<br />

clouds have been reported in the atmosphere of HD189733b. We will present the first<br />

results of a program aiming at detecting and characterizing clouds in hot-Jupiter<br />

atmospheres. We use joint space-based visible+IR occultation and phase-curve<br />

photometry to reconstruct low-resolution maps of thick clouds. We will discuss the possible<br />

formation scenarios for these clouds and explore the degeneracies involved in the retrieval<br />

of the particles properties (coverage, size distribution, vertical extent, composition, shape,<br />

etc.). We will finally discuss how near-to-come space- and ground-based facilities will<br />

contribute to the detailed characterization of these clouds.<br />


Characterising Exoplanets Using Kepler Phase-Curves!<br />

Lisa Esteves — University of Toronto!<br />

Although the Kepler mission is mainly aimed at searching for exoplanet transits, its highprecision<br />

photometry and long-term monitoring of the same field, makes it ideal to use for<br />

phase-curve measurements. Recently, using almost four years of Kepler data, we have<br />

been able to measure the phase-curve of eight Kepler objects. For five of these we<br />

present the very first phase-curve measurements, while for the other three objects we<br />

present greatly refined parameters. In addition we demonstrate how phase-curves<br />

measurements can be used as a very powerful tool for ruling out false positives within the<br />

Kepler planet candidate population.<br />

Measuring the reflection signal of HD189733b!<br />

Tom Evans — Oxford University!<br />

The multi-wavelength reflection signal of an exoplanet provides a valuable insight into the<br />

composition and structure of its atmosphere. In this talk, I will describe our measurement<br />

of a secondary eclipse of HD189733b across the 290-570nm wavelength range, made<br />

using HST/STIS. We found that the albedo of the planet decreases towards longer<br />

wavelengths in this range from approximately Ag=0.4 to Ag

data reduction stage crucial to our current understanding of exoplanet atmospheres. This<br />

has prompted the development of new, sophisticated techniques to robustly extract signals<br />

from transit data, and also a drive to use new observing facilities to re-observe and confirm<br />

exoplanet signals. Ground-based telescopes are now playing an increasingly prominent<br />

role, with multi-object spectrographs enabling differential ground-based spectrophotometry.<br />

These observations are now providing similar precision to space-based observations<br />

where appropriate comparison stars are available, and should allow us to verify spacebased<br />

spectra and ease our dependence on single instruments. Here, we present efforts<br />

to measure transmission spectra using the Gemini telescopes, with the GMOS multi-object<br />

spectrographs, and discuss how we extract the atmospheric signals in the presence of<br />

complex noise sources. We report transit observations of WASP-29, HAT-P-32 and<br />

(possibly) HAT-P-33, reaching sufficient precision to probe atmospheric features. These<br />

reveal featureless spectra possibly caused by the presence of clouds in the upper<br />

atmospheres, although further observations are required to confirm this.<br />

On the Statistical Significance of Trends in Exoplanetary Emissions!<br />

Joseph Harrington — University of Central Florida<br />

We have examined the fluxes of exoplanetary atmospheres as measured during<br />

secondary eclipses. Cowan and Agol (2011) and we (Harrington et al. 2007, 2010, 2011,<br />

2012, 2013) have noted that at equilibrium temperatures above about 2000 K (zero<br />

albedo, uniform redistribution), observed exoplanet fluxes are substantially higher than<br />

even the elevated equilibrium temperature predicts. With a substantial increase in the<br />

number of atmospheric flux measurements, we can now test the statistical significance of<br />

this trend. We can also cast the data on a variety of axes to search further for the physics<br />

behind both the jump in flux above about 2000 K and the wide scatter in fluxes at all<br />

temperatures.<br />

Enshrouded Close-In Exoplanets<br />

Carole Haswell — Open University<br />

Our near-UV HST observations of the extreme hot Jupiter WASP-12b revealed<br />

extended exospheric gas overfilling the planet\s Roche lobe and causing<br />

reproducible enhanced transit depths at 65 distinct wavelengths. There is<br />

complete absorption, i.e. zero emergent flux, in the cores of the very strong<br />

MgII h&k lines at all observed orbital phases.<br />

I will present several lines of evidence to show this is due to diffuse gas lost<br />

from WASP-12b, which enshrouds the entire planetary system. Our results suggest a new<br />

interpretation of the known correlation between hot Jupiter atmosphere type and host star<br />

activity as indicated by the cores of the very strong CaII H&K lines. I will present recent<br />

observations of the putative evaporating rocky exoplanet KIC 1255b. WHT/ULTRACAM<br />

simultaneous multiwavelength light curves obtained in July 2013 have implications for the<br />

dust scattering function,an empirical upper limit on the size of the planet, and the limitcycle<br />

mechanism which modulates the observed dust extinction. We used CFHT/<br />

ESPaDOnS to perform transmission spectroscopy searching for metal rich vapour<br />

expected to co-exist with the dust as the gas phase component of the planetary mass loss.<br />

Finally I will discuss the general implications of these findings for the Galaxy’s population<br />

of planets and for studies of star-planet interactions.<br />


Characterization of Exoplanets using Planetary Radial Velocimetry!<br />

Hajime Kawahara — The University of Tokyo!<br />

Recently radial velocity curves of exoplanets have been measured with the aid of the high<br />

dispersion instrument CRIRES on VLT (e.g. Snellen et al. 2010, Brogi et al. 2012, Rodleret<br />

al. 2012, Birkby et al. 2013). I consider the effect of planet’s spin on the planetary radial<br />

velocity. With simple assumptions, I find that the radial velocity curve is distorted by the<br />

planetary spin and this anomaly is characterized by spin radial velocity at equator and a<br />

projected angle on a celestial plane between the spin axis and the axis of orbital motion<br />

(Kawahara 2012). I will discuss the feasibility of the precise planetary radial velocity<br />

measurement for such as the spin measurement, with possible instruments in near future.<br />

Polarimetry of transiting exoplanetary systems!<br />

Nadiia!Kostogryz — Kiepenheuer-Institut für Sonnenphysik!<br />

Since the discovery of the first extrasolar planet, methods of their detection and<br />

characterization are rapidly developing. The best-characterized planets are so far those<br />

which were detected by different methods. Thanks to the recent high-accuracy polarimetric<br />

instruments, polarimetry has become an independent technique for characterizing<br />

exoplanetary systems as it yields information inaccessible to other methods. As was<br />

shown observed polarization variability due to scattering in the planetary atmosphere<br />

reveals the orbital period of the planet, inclination, eccentricity, orientation of the orbit as<br />

well as the nature of scattering particles in the planetary atmosphere.<br />

We present and discuss another polarimetric effect caused by a planet transiting the stellar<br />

disk and, therefore, breaking its symmetry and resulting in linear polarization of a partially<br />

eclipsed star. Such an effect was predicted in 1950 for binary stars, and it was first<br />

detected in the eclipsing binary Algol. Estimates of this effect for transiting planets were<br />

made only recently. In particular, we demonstrated that the maximum polarization for one<br />

of the brightest transiting planets HD189733b strongly depends on the centre-to-limb<br />

variation of linear polarization for the host star. However, observational and theoretical<br />

studies of the limb polarization have been largely concentrated on the Sun. As was shown<br />

in our previous study, we expect to observe a larger centre-to-limb linear polarization for<br />

cooler stars. Here we solve the radiative transfer problem for polarized light and simulate<br />

the centre-to-limb polarization for stars of different spectral classes taking into account<br />

various opacities. Knowing stellar limb polarization is also necessary for evaluating stellar<br />

contribution when interpreting scattering polarization from spatially unresolved planets at<br />

elongations. In addition, the radius of the grazing planet can be determined from transit<br />

polarimetry when transit photometric data become unreliable. Employing our simulations<br />

for all transiting exoplanets we select most promising targets for future polarimetric<br />

observations.<br />

Detecting Exoplanetary Magnetic Fields<br />

Joe Llama — University of St Andrews<br />

In this work we explore the possibility of detecting magnetic fields around extrasolar<br />

planets using asymmetries in their transit light curves. Observations of the very close-in,<br />

highly inflated planet WASP-12b have revealed an asymmetry in the near-UV light curve<br />

when compared to the optical transit. It has been suggested that this asymmetry may be<br />

caused by the stellar wind colliding with the magnetosphere of the planet, resulting in the<br />

formation of a magnetospheric bow shock. We show how modelling such a shock allows<br />


us to reproduce this transit asymmetry and to place constraints on the magnetic field<br />

strength of the planet.<br />

Characterizing Exoplanet Atmospheres with HST/WFC3<br />

Avi Mandell — NASA GSFC !<br />

The Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) provides the<br />

potential for spectroscopic characterization of molecular features in exoplanet<br />

atmospheres, a capability that has not existed in space since the demise of NICMOS on<br />

HST and the IRS on Spitzer. We present an analysis of transit spectroscopy for three<br />

extrasolar planets observed during the HST Cycle 18: WASP-12 b, WASP-17 b, and<br />

WASP-19 b. WASP-12 b and WASP-19 b are two of the hottest exoplanets discovered to<br />

date, while WASP-17 b has a much lower equilibrium temperature but has one of the<br />

largest atmospheric radii of known transiting planets; measurement of molecular<br />

absorption in the atmospheres of these planets offers the chance to explore several<br />

outstanding questions regarding the atmospheric structure and composition of these highly<br />

irradiated, Jupiter-mass objects. The observations cover a single primary transit for each<br />

planet, and we analyze the data using a strategy that allows us to correct for channel- or<br />

wavelength-dependent instrumental effects by utilizing the band-integrated time series and<br />

measurements of the drift of the spectrum on the detector over time. We achieve almost<br />

photon-limited results for individual spectral bins, but the uncertainties in the transit depth<br />

for the the band-integrated data are exacerbated by the uneven sampling of the light curve<br />

imposed by the orbital phasing of HST observations. Our final transit spectra for all three<br />

objects are consistent with the presence of a broad absorption feature at 1.4 microns most<br />

likely due to water. However, the amplitude of the absorption is less than that expected<br />

based on previous observations with Spitzer, possibly due to hazes absorbing in the NIR<br />

or non-solar compositions. The degeneracy of models with different compositions and<br />

temperature structures combined with the low amplitude of any features in the data<br />

preclude our ability to place unambiguous constraints on the atmospheric composition, but<br />

future observations with WFC3 to improve the S/N and/or a comprehensive multiwavelength<br />

analysis will allow us to better distinguish between different models.<br />

HST/STIS Transmission Spectral Survey: Probing the Atmospheres of HAT-P-1b and<br />

WASP-6b!<br />

Nikolay Nikolov — University of Exeter<br />

We present optical to near-infrared transmission spectra of HAT-P-1b and WASP-6b, part<br />

of a Large HST/STIS hot Jupiter transmission spectral survey (P.I. David Sing). The<br />

spectra for each target cover the regimes 290-570nm and 524-1027nm, with resolving<br />

power of R = 500. The HAT-P-1b data is coupled with a recent HST/WFC3 transit,<br />

spanning the wavelength range 1.087-1.687 micron (R=130), acquired in spatial scan<br />

mode. The WASP-6b data is complemented with Spritzer/IRAC 3.6 and 4.5 micron transit<br />

observations, part of a comparative exoplanetology program (P.I. Jean-Michel Desert). The<br />

transmission spectrum of HAT-P-1b shows a strong absorption signature shortward of<br />

550nm, with a strong blueward slope into the near-UV. We detect atmospheric sodium<br />

absorption at a 3.3-sigma significance level, but see no evidence for the potassium<br />

feature. The red data implies a marginally flat spectrum with a tentative absorption<br />

enhancement at wavelength longer than ~850nm. The combined STIS and WFC3 optical<br />

to NIR spectra differ significantly in absolute radius level (4.3+/-1.6 pressure scale<br />

heights), implying strong optical absorption in the atmosphere of HAT-P-1b. The optical to<br />


near-infrared difference cannot be explained by stellar activity, as simultaneous stellar<br />

activity monitoring of the G0V HAT-P-1b host star and its identical companion show no<br />

significant activity that could explain the result. The red transmission spectrum of<br />

WASP-6b is flat with tentative detection of sodium and potassium. We compare both<br />

spectra with theoretical atmospheric models which include haze, sodium and an extra<br />

optical absorber in the case of HAT-P-1b. We find that both an optical absorber and a<br />

super-solar sodium to water abundance ratio might be a scenario explaining the HAT-P-1b<br />

observations.<br />

Characterizing Hot Jupiter Atmospheres with Ground-Based Facilities: Instrument<br />

Performance and New Results<br />

Lisa Nortmann — University of Göttingen<br />

Transiting planets are of particular interest for exoplanet atmosphere science as the<br />

geometry of their orbits enables us to investigate atmospheric transmission spectra.<br />

During transit the upper layers of an exoplanet atmosphere are penetrated by its host<br />

star’s light. As a consequence the fingerprint of the atmospheric composition at the<br />

terminator region can be observed in form of a color dependent variation in the occultation<br />

depth. One of the biggest remaining challenges of multi-color transit observations is the<br />

proper removal of systematic noise signals. Such signals are frequently found to distort the<br />

light curves in data of both ground-based and space-based origin and in many cases their<br />

source is not well understood.<br />

Our group uses the ground-based facilities ESO/VLT+FORS2 and the Spanish 10-meter<br />

telescope GranTeCan+OSIRIS to probe the atmosphere of hot Jupiters with the technique<br />

of multi-object spectrophotometry. I will address our new findings regarding the source and<br />

nature of instrument specific systematics that we noticed to commonly affect data taken<br />

with these two instruments. Furthermore, I will introduce our approach to the correction of<br />

these noise signals, which allows us to retrieve high quality spectrophotometric data. As an<br />

example I will present the transmission spectra of the two hot Jupiters WASP-17b and<br />

HAT-P-32b which we obtained in the optical wavelength region between 500 and 1000 nm.<br />

In this broad wavelength interval the transmission spectra of hot Jupiters are predicted to<br />

exhibit sodium, potassium, water and titanium/vanadium oxide absorption. The abundance<br />

of these atmospheric species is of particular interest, as they serve as good indicators for<br />

the prevalent temperature and, consequently, can help to shed light on the mechanisms of<br />

heat re-distribution between the planet’s day and night side.<br />

A Secondary Eclipse Survey of the Hottest Exoplanets with Palomar and Spitzer!<br />

Joseph G. O'Rourke — California Institute of Technology<br />

Combined ground- and space-based secondary eclipse observations provide an<br />

invaluable window on the dayside emission spectra for transiting exoplanets, as<br />

demonstrated by recent studies of WASP-12b. Here, we present preliminary results from<br />

our survey of hot Jupiters with relatively high temperatures (>2000 K). We utilize<br />

secondary eclipse photometry at 3.6 and 4.5 µm taken with the IRAC camera aboard the<br />

Spitzer Space Telescope during the warm Spitzer mission and in the H and Ks bands with<br />

the WIRC camera at the Palomar 200-inch Hale Telescope. We discuss how the<br />

installation of a new diffusing filter in the WIRC filter wheel mitigates many of the<br />

systematic problems encountered during ground-based observations. With multiwavelength<br />

photometry and spectroscopy for a large sample of hot Jupiters, we can<br />

search for trends in atmospheric characteristics, including elemental abundances, C/O<br />


atios, and temperature profiles, that might be important clues to their formation and<br />

evolution.<br />

Models of exoplanet evaporation<br />

James! Owen — Canadian Institute for Theoretical Astrophysics<br />

Given the numerous exoplanets discovered at close separations to their parents stars,<br />

where the stellar UV & X-ray radiation fields can heat the upper layers of the planets<br />

atmosphere to 10 4 K, evaporation is bound to occur. I will discuss evaporation in the<br />

hydrodynamic limit which can be driven by either the EUV or X-ray radiation, and the<br />

associated mass-loss rates. I will argue that evaporation of close-in exoplanets does not<br />

occur in `energy-limited' sense where PdV work dominates the energy loss, but that<br />

radiative cooling and recombinations are dominant energy sinks. Finally, I will present the<br />

results of multi-dimensional calculations and discuss the role planetary and stellar<br />

magnetic fields play in exoplanet evaporation, along with the long term impact of<br />

evaporation on exoplanets.<br />

Transit Transmission spectroscopy with GTC: First results<br />

Enric Palle — Instituto de Astrofisica de Canarias<br />

Our group is presently conducting an observational campaign, using the 10-meter Gran<br />

Telescopio Canarias (GTC), to obtain long-slit spectra in the optical range of several<br />

planetary host stars (and a reference star) during a transit event. The GTC instrument<br />

OSIRIS consists of two CCD detectors with a field of view of 7.8 X 7.8 arcmin. We used<br />

OSIRIS in its long-slit spectroscopic mode, selecting the grism R=1000 which covers the<br />

spectral range of 520-1040 nm, and a custom-built slit of 12 arcsec of width. A Markov<br />

Chain Monte Carlo (MCMC) Bayesian approach is used for the transit fitting, and the level<br />

of red noise in the light curves is estimated using the method of Winn et al. (2008). Here,<br />

we will present refined planet parameters, planet color signatures, and the transmission<br />

spectrum of a set of know transiting exoplanets, namely: WASP-43b, HAT-P-12b,<br />

WASP-48b, and KIC 12557548b. With our instrumental setup, GTC has been able to<br />

reach precision down to 250 ppm (WASP-48b, V=11.06 mag) for each color light curve 15<br />

nm wide. We will also discuss the capabilities and advantages of GTC as tool for the<br />

follow up of faint Kepler targets, such as KIC 12557548b. The light curves obtained for this<br />

object with low resolution gratings allow us to reach 300 ppm in a 4-min sampled curve,<br />

thus revealing the detailed shape, small scale structures, and color information of<br />

individual transits of KIC12557548b.<br />

Characterisation of exoplanet atmospheres with KMOS<br />

Hannu Parviainen — University of Oxford<br />

We present our preliminary results and experiences with the KMOS (K-Band Multi-Object<br />

Spectrometer) instrument in the characterisation of exoplanet atmospheres using transit<br />

transmission spectroscopy, and detail our approach to the data reduction and analysis.<br />

Our experiences are mainly based on transits observed during the instrument's<br />

commissioning phase, and the investigation of the KMOS instrument's applicability to<br />

transit spectroscopy was an important secondary goal along with the science driver.<br />


Transit transmission spectroscopy offers a direct way to study the atmospheric properties<br />

of transiting exoplanets. However, the variations in the transit depth are small, of order<br />

10 -4 , and disentangling the minute changes in the transit signal from the systematic noise<br />

signals is all but trivial.<br />

KMOS is a NIR multi-object spectrometer capable of observing spatially resolved spectra<br />

of 24 2.8x2.8 arcsecond freely positionable fields simultaneously. Each field is<br />

implemented using an integral field unit (IFU) with a 14x14 pixel spatial resolution. The<br />

ability to observe simultaneous spectra from a number of separate fields allows for high<br />

flexibility in the selection of comparison stars for relative spectroscopy, facilitating the<br />

reduction of common systematics. However, the use of IFUs with small spatial footprints<br />

creates also new challenges that need to be overcome before the instrument's full<br />

potential can be used.<br />

Direct evidence of the inversion layer in HD 209458 b from high-dispersion<br />

spectroscopy<br />

Henriette Schwarz — Leiden University<br />

We present preliminary results from high-resolution thermal emission spectra of the hot<br />

Jupiter HD 209458 b. This bright transiting planet is interesting because it is a good<br />

candidate for a hot Jupiter with an inversion layer in its atmosphere. Snellen et al. (2010)<br />

observed HD 209458 b during a transit with high-resolution spectra at wavelengths around<br />

2.3 micron, and they detected molecular absorption from carbon-monoxide. The new dataset<br />

again uses the CRIRES spectrograph at VLT. This time we are looking at the thermal<br />

emission from the hot day-side of the planet at phases close to the secondary eclipse. We<br />

see no evidence for CO absorption in the thermal spectra, but an interesting hint of CO<br />

emission — the tell-tale sign of a thermal inversion layer high up in the atmosphere of this<br />

planet.<br />

Atmospheric characterization of the hot Jupiter Kepler-13b<br />

Avi Shporer — Caltech/JPL<br />

Kepler-13b (= KOI-13.01) is a unique transiting hot Jupiter. It is one of very few known<br />

short-period (1.76 day) planets orbiting a bright (V~10 mag) A-type star. Therefore, it is<br />

among the hottest and brightest planets currently known, motivating the study of its<br />

atmosphere. The availability of Kepler data allows us to measure the planet's occultation<br />

(secondary eclipse) and phase curve, in the optical, with very high precision, which we<br />

combine with occultations observed by the Warm Spitzer Mission at 3.6 micron and 4.5<br />

micron, and a ground-based occultation observation by the Wide-field Infra-Red Camera<br />

(WIRC), mounted on the Palomar 200 inch telescope, at the Ks band (~2.1 micron). Since<br />

the host star is the primary component of a visual binary system with ~1 arcsec separation,<br />

the two similar stars are fully blended in all our photometry. To correct the observed<br />

occultation depths for this dilution we modeled the stellar spectra, from the optical to the<br />

infrared, based on Keck/HIRES spectra that resolved the two stars. Our preliminary results<br />

indicate that the planetary atmosphere has a relatively high geometric albedo (Ag ~0.3)<br />

and a highly efficient heat distribution from the day side to the night side (epsilon ~0.9).<br />

This represents a deviation from previous studies in which the most highly irradiated hot<br />

Jupiters were found to have inefficient recirculation of energy from the day to the night<br />

sides. We also present revised atmospheric parameters for the planet-hosting star in this<br />


triple stellar system, and a revised planetary mass estimate based on the beaming effect<br />

and the tidal ellipsoidal distortion observed in the Kepler phase curve.<br />

Revealing Distant Worlds with Ground-Based Spectroscopy<br />

Kevin Stevenson — University of Chicago<br />

Uncovering the fundamental properties of exoplanetary atmospheres requires highprecision<br />

spectroscopy over a broad range of wavelengths. We are poised to make<br />

significant advances in our understanding of their composition and chemistry using<br />

currently-available, visible and near-infrared multi-object spectrographs attached to some<br />

of the largest telescopes in the world. With facilities such as Gemini, Keck, and Magellan,<br />

we are conducting an intensive survey of a representative sample of exoplanets to<br />

measure their transmission and dayside emission spectra. We will present high-quality<br />

spectra for several recently-observed exoplanets and discuss how these data constrain<br />

the molecular abundances, thermal profiles, and relevant chemistries of these planetary<br />

atmospheres.<br />

Updated Spitzer Secondary Eclipse Spectroscopy of HD189733b<br />

Kamen Todorov — ETH Zürich<br />

We analyze Spitzer Space Telescope time-series spectroscopy observations of HD<br />

189733b during 18 secondary eclipses at wavelengths between 5 and 14 microns. These<br />

measurements comprise the most extensive emission spectrum of any exoplanet to date.<br />

While some of these data sets have been analyzed previously by Grillmair et al. (2008),<br />

we examine eight of them for the first time. We remove the systematic effects from the<br />

spectral light curves using the most advanced techniques available, and measure the<br />

secondary eclipse depths as a function of wavelength. We use a modified version of a<br />

radiative transfer code by Richardson et al. (2003) to calculate three emergent spectrum<br />

models and compare our observational results with them, and with the best fit model<br />

(Burrows et al. 2008) adopted by Grillmair et al. in their earlier investigation. We can<br />

confidently exclude isothermal and gray atmospheres and confirm the water feature<br />

detected by Grillmair et al.<br />

Phase curves of close-in Kepler planets<br />

Vincent Van Eylen — Aarhus University!<br />

The Kepler satellite has provided a wealth of new data on transiting exoplanets. Its<br />

unprecedented precision allows for more than just analyzing the transit: for hot planets in<br />

an orbit of only a few days, the parts-per-million precision allows for the detection of<br />

planetary light throughout the full phase, as well as its absence during the secondary<br />

eclipse. For those tidally locked planets, the increase in received flux as we view more and<br />

more of the planet's day side allows us to make statements on the planetary reflection<br />

(albedo) and temperature. Measuring the depth of the occultation leads to estimates on<br />

the temperature of the (cold) planetary nightside. I present preliminary results on a<br />

comparative study of the sample of close in transiting exoplanets which were observed by<br />

Kepler.<br />


Water in the atmosphere of hot-Jupiter exoplanets<br />

Hannah Ruth! Wakeford — University of Exeter<br />

Using the Hubble Space Telescope’s WFC3 camera with an infrared low resolution grism,<br />

we observed a number of hot Jupiters from 1.1-1.7 µm, probing primarily the H2O<br />

absorption band at 1.4 µm. H2O is a key molecule for constraining hot-Jupiter<br />

atmospheres with the atmospheric C/O ratio playing a pivotal role in the relative H2O<br />

abundance. We present a variance in these hot Jupiter atmospheres with a strong H2O<br />

detection in the upper atmosphere of HAT-P-1b and new results from WASP-31b. The<br />

computed transmission spectra show a startling diversity in the observed abundance of<br />

H2O in the atmosphere of close-in giant planets allowing us to explore the nature of their<br />

relative environments.<br />

The 4.5 micron phase curve of HD 209458b!<br />

Robert Zellem — Lunar and Planetary Laboratory - University of Arizona!<br />

The hot Jupiter HD 209458b is one of the most favorable targets for full-orbit phase curve<br />

observations, as it is one of the brightest systems (V-mag = 7.65, K-mag = 6.308), has a<br />

large planet-to-star contrast, and offers a high signal-to-noise ratio and the ability to make<br />

high-precision measurements. This planet also serves as the archetype for a class of<br />

planets that have dayside temperature inversions; the differences between this class of<br />

planets and those lacking inversions (including HD 189733b) are currently not wellunderstood.<br />

Here we present the first full-orbit phase curve of HD 209458b observed with<br />

the Spitzer/IRAC 4.5 micron photometric band. Our data, which includes one primary<br />

transit and two secondary eclipses, was reduced with a pixel-mapping method to get within<br />

1.145 times the photon noise limit. We measure the brightness temperature of the<br />

observed phase curve. The results are modeled with radiative transfer models along with<br />

other primary transit and secondary eclipse data to determine the pressure level of the<br />

emissions. We then compare these results to predictions from global circulation models,<br />

including those where magnetic effects and thermal inversions are present in order to<br />

determine the effect that HD 209458b\s dayside temperature inversion has on its<br />

atmospheric circulation and chemistry.<br />


Effects of clouds on reflection properties of hot Jupiters!<br />

Nadine Afram — Kiepenheuer Institut für Sonnenphysik, Freiburg<br />

The presence of clouds in exoplanetary atmospheres may dramatically change their<br />

reflectivity properties. This can be detected during secondary eclipses and with the help of<br />

polarimetric techniques, independently of planet transits. Here, we model polarimetric<br />

phase curves and secondary eclipses for some very hot Jupiters with orbital periods<br />

shorter than 3 days (e.g., WASP-19b, HD189733b) using model atmospheres with and<br />

without clouds. We empirically adjust pressure-temperature profiles and the cloud<br />

composition and height and investigate how polarization and eclipse curves depend on<br />

atmosphere parameters. In particular, we consider such molecules and condensates as ,<br />


OH, H2, CO, CO2, CH4, NH3, MgO, MgSiO3, Mg2SiO4, Al2O3, etc. We compare our results with<br />

available polarimetric and photometric measurements for hot Jupiters.<br />

Testing radiative transfer schemes for use in global circulation models of hot<br />

Jupiters!<br />

David Skålid!Amundsen — University of Exeter!<br />

Several studies which have used adapted Global Circulation Models (GCMs) to interpret<br />

observations of hot Jupiters have now been published. Almost all of these studies involve<br />

simplified dynamical (e.g shallow water or primitive equations) and radiative transfer<br />

schemes (temperature forcing, grey or band-averaged absorption coefficients). We are<br />

adapting the UK Met Office GCM, the Unified Model, which solves the full 3D compressible<br />

Euler equations and includes a frequency dependent radiative transfer scheme (invoking<br />

the two-stream approximation and correlated-k method) for the study of hot Jupiters.<br />

We will discuss the adaptation of the radiative transfer scheme and the tests we have<br />

performed to verify its accuracy. By comparing to more accurate discrete-ordinate line-byline<br />

calculations we will demonstrate that this scheme yields fairly accurate fluxes and<br />

heating rates overall. In some cases, however, there are significant deviations, and we find<br />

the use of band-averaged absorption coefficients to be very inaccurate. Lastly, I will<br />

present some of the first results we have obtained after recoupling the dynamical core and<br />

radiative transfer schemes.<br />

An Open Source Python Thermochemical Equilibrium Abundances Code!<br />

Jasmina Blecic — University of Central Florida<br />

We present a Thermochemical Equilibrium Abundances code (TEA) that calculates the<br />

equilibrium abundances of the molecular species present at a given temperature and<br />

pressure in a planetary atmosphere. There are two approaches to calculating<br />

thermochemical equilibrium: by using equilibrium constants and reaction rates or by<br />

minimizing the free energy of the system. Although chemical equilibrium can be calculated<br />

almost trivially for several reactions present in the system, as the number of reactions<br />

increases, the number of equilibrium-constant relations becomes difficult to solve<br />

simultaneously. An advantage of the free-energy-minimization method is that each<br />

species present in the system can be treated independently, without specifying<br />

complicated sets of reactions. Therefore, just a limited set of equations needs to be<br />

solved. TEA is based on the Gibbs-free-energy minimization calculation, originally<br />

developed by White et al. (1958) and Eriksson (1971). The code is written entirely in<br />

Python and is available to the scientific community under an open-source license.<br />

VSTAR Models of a Hot Jupiter<br />

Kimberly Bott -- University of New South Wales<br />

Past analysis of HD 189733b's atmosphere has been a cause for some debate, with<br />

conflicting findings regarding polarized light, carbon dioxide and sodium abundances and<br />

the presence of a high altitude haze. I will present our model of HD 189733b's atmosphere<br />

using VSTAR (Versatile Software for Transfer of Atmospheric Radiation), a robust, line-byline,<br />

multiple scattering radiative transfer solution in a modular program, utilitizing its own<br />

chemical equilibrium model. Since the effective temperature of the planet is expected to be<br />

approximately 1100K, newly available high-temperature spectral line lists were used. The<br />


planet’s dayside, terminator and reflected polarized light are modeled and compared to<br />

available data.<br />

Circumplanetary Jet Formation, Characteristics, and Observational Diagnostics<br />

Ian Dobbs-Dixon — University of Washington!<br />

Ubiquitous among multidimensional simulations of highly irradiated gas-giant planets is the<br />

development of circumplanetary jets in the equatorial region of the planet. These jets,<br />

many of which become supersonic, are the dominant dynamical feature, helping to shape<br />

all observable features and perhaps influencing the thermal evolution of the entire planet.<br />

However, observations of irradiated gas-giants suggest that not all planets form such jets.<br />

Despite their importance for interpreting observations, the precise physical mechanism for<br />

forming and sustaining jets remains an area of active research. We lay out a linear theory<br />

for the formation of these jets and compare our predicted behavior to results from<br />

multidimensional radiative-hydrodynamical simulations. We then further discuss a novel<br />

observational technique for detecting these jets during a single eclipse. A faster method of<br />

detecting a jet will allow for a much broader survey of systems, hopefully shedding light on<br />

the physical parameters of the system that help or hinder jet formation.<br />

Escape of Hydrogen from HD209458b!<br />

Justin!Erwin — University of Arizona!<br />

Recent modeling of the atmosphere of HD209458b has been used to interpret the Lymanline<br />

and other observations during transits. Koskinen et al. (2010) used a hydrostatic<br />

density profile in the thermosphere combined with the Voigt profile to estimate the Lymanalpha<br />

transit depths for an array of model parameters. A detailed photochemical-dynamical<br />

model of the thermosphere was developed by Koskinen et al. (2013a) and used to again<br />

estimate model parameters to fit not only the Lyman-alpha transits, but also the transits in<br />

the O I, C II and Si III lines (Koskinen et al., 2013b). Recently, Bourrier and Lecavelier<br />

(2013) modeled the escape of hydrogen from the extended atmospheres of HD209458b<br />

and HD189733b and used the results to interpret Lyman-alpha observations. They<br />

included acceleration of hydrogen by radiation pressure and stellar wind protons to<br />

simulate the high velocity tails of the velocity distribution, arguing that the observations are<br />

explained by high velocity gas in the system while Voigt broadening is negligible.<br />

In this work we connect a free molecular flow (FMF) model similar to Bourrier and<br />

Lecavelier (2013) to the results of Koskinen et al. (2013b) and properly include absorption<br />

by the extended thermosphere in the transit model. In this manner, we can interpret the<br />

necessity of the various physical processes in matching the observed line profiles.<br />

Furthermore, the transit depths of this model can be used to re-evaluate the atmospheric<br />

model parameters to determine if they need to be adjusted due to the existence of the<br />

extended hydrogen tail.<br />

Thor: A GPU code for simulating exoplanetry atmospheres<br />

Simon!Grimm — University of Zürich<br />

We present an implementation of a three-dimensional general circulation model (GSM),<br />

designed for simulating exoplanetary atmospheres, running fully parallel on Graphics<br />

Processing Units (GPU’s). The Code is developed for the <strong>Exoclimes</strong> Simulation Platform<br />

(ESP) and will be available as open source software. Thor solves the three dimensional<br />


non hydrostatic Euler equations on a modified Yin-Yang grid, which consists of an<br />

equatorial belt and two polar caps, which are patched together using a fully conservative<br />

zonal interface algorithm, described by Wang (1995). The individual grids are solved with a<br />

horizontal explicit and vertical implicit (HEVI) finite difference scheme, where the vertical<br />

solution can be computed analytically. In this poster we present the implemented scheme<br />

and show as well results of the first tests, including a quantification of the conservation of<br />

energy, mass and momentum.<br />

Compared to other available CPU codes, Thor shows a speed-up of around one<br />

magnitude. Thor is written in Cuda C and runs on all Nvidia GPU's.<br />

The <strong>Exoclimes</strong> Simulation Platform!<br />

Kevin! Heng! — Center for Space and Habitability, University of Bern<br />

!<br />

The state of the art in performing 3D simulations of exoplanetary atmospheres centers<br />

around adapting GCMs (general circulation models), originally designed for the study of<br />

Earth. These Earth-centric tools suffer from fundamental shortcomings, including Earthcentric<br />

assumptions, the inability to model shocks, the exclusion of magnetic fields and the<br />

treatment of radiative transfer as if the atmosphere is static. We offer an alternative<br />

perspective: the design and development of a set of publicly available, theoretical and<br />

simulational tools for the general exoplanet community, partly to combat the growing "black<br />

box" culture in our field. I give a brief and broad review of the <strong>Exoclimes</strong> Simulation<br />

Platform (ESP), focusing on the GCMs and radiative transfer tools that are currently in<br />

development. I will also explain our decision to build the ESP entirely on GPUs, which<br />

gives our open-source tools a speed-up of at least an order of magnitude (two orders of<br />

magnitude for radiative transfer). I will describe how we plan to involve the community via<br />

a web portal (www.exoclime.org), which includes a Facebook page for soliciting feedback.<br />

VIPER: Toward a universal model for planetary climate<br />

Nicolas Iro — University of Hamburg<br />

With the discovery of an increasing number of planets outside our Solar System, we are<br />

becoming familiar with physical conditions and atmospheric compositions that span a<br />

much wider range that what covered by the planets of our solar system. Non-exhaustive<br />

examples are equilibrium temperatures ranging from 50K (Neptune) to over 3000K<br />

(WASP-12b, WASP18b); orbital eccentricity, ranging from 0-0.1 for solar system planets<br />

(except Mercury) and circularized close-in hot Jupiters to e = 0.93 (HD80606b). Other<br />

parameters relevant for atmospheric dynamical features are also quite diverse: the Rhines<br />

length and Rossby length are, e.g., much smaller than the planet radii for Solar-System<br />

planets, while they are comparable to the planetary radii for hot Jupiters and Neptunes,<br />

meaning that in the latter case typical circulation features are global. It seems timely and<br />

urgent to try to frame in a common framework our understanding of such a large variety of<br />

atmospheric conditions. We will present VIPER, the Versatile Interactive PlanetSimulator<br />

for Extrasolar Research. This project, under development, aims at developing the Planet<br />

Simulator, an already flexible climate model to a new level of modularity. In the next phase<br />

of the implementation, we will remove all parameterization pertaining to Earth, allowing for<br />

instance to study any planetary rotation rate and add a simple yet precise radiative<br />

scheme based on the k-distribution coefficients. This will allow us to model the climate on<br />

a variety of planetary conditions from early Mars to Super-Earths.<br />


Modelling of the Emission Spectrum of WASP-19b<br />

Lucyna Kedziora-Chudczer — University of New South Wales<br />

The VSTAR radiative transfer code was used to model the emission spectrum of the one<br />

of the most irradiated hot-Jupiters, WASP-19b. We examined models with different<br />

pressure-temperature profiles and C/O abundances ratios. We find that models with<br />

carbon enrichment above solar match the available data best. We also included upperatmosphere<br />

haze of varied particle sizes and find that particles

ongoing. This will help us understand, for given circumstances, how a planetary magnetic<br />

field could alter the wind structure on hot Jupiters and its effects on day-night temperature<br />

variations and planetary radii.<br />

Extended ionospheres on extrasolar giant planets!<br />

Tommi! Koskinen — University of Arizona<br />

Recent work on close-in extrasolar giant planets (EGPs) raises the possibility that their<br />

atmospheres are significantly affected by ion drag and Joule heating arising from thermal<br />

ionization of their atmospheres (e.g., Cho 2008, Batygin et al. 2010, Perna et al. 2010a,b).<br />

It is unclear, however, if large scale current systems are supported in the relatively weakly<br />

ionized atmospheres of close-in EGPs. We explore thermal ionization and photoionization<br />

of EGP atmospheres, and use the results to constrain the electrodynamic regimes at<br />

pressures ranging from 1 bar to the escaping thermosphere. In line with planetary<br />

atmospheres in the solar system, we find that the coupling of the ions to the neutral<br />

atmosphere is important at all pressure levels. Assuming a magnetic field similar to that of<br />

Jupiter, we find that both the electrons and ions are collisionally coupled to the neutrals<br />

below the 0.1-1 mbar level, but significant ion drag and Joule heating are possible at<br />

pressures lower than this. The conductivities that we calculate, however, imply that the<br />

upper atmospheres of close-in EGPs occupy a regime closer to the solar chromosphere<br />

than planetary ionospheres in the solar system — even at relatively high pressures in the<br />

stratosphere. Nevertheless, the generalized Ohm’s law for partly ionized media is still<br />

valid and we explore the resulting current systems based on this assumption.<br />

3-D modeling of atmospheric escape from Hot Jupiters !<br />

Alain Lecavelier — Institut d'Astrophysique de Paris!<br />

Transit observations in the Lyman-alpha line of the hot Jupiters HD209458b and<br />

HD189733b revealed strong signatures of neutral hydrogen escaping the planet's<br />

atmospheres. We will present our 3D particle model of the dynamics of the escaping<br />

atoms, which is used to calculate theoretical absorption profiles, and can be directly<br />

compared to the observations to constrain the physical conditions at high altitudes in the<br />

exosphere (such as the escape rate and the stellar ionizing flux). Recently, this model has<br />

also been used to interpret the observation of neutral magnesium probing the<br />

thermosphere-exosphere transition region. Simulations show the major influence of the<br />

stellar radiation pressure on the structure of the escaping gas cloud, which can also be<br />

shaped by stellar wind interactions, planetary gravity and self-shielding effects. This results<br />

in spectro-temporal variations of the absorption profile that could be used to further<br />

characterize the atmospheric escape. On a wider scale, our model can be used as a<br />

predictive tool to identify evaporating exoplanets with high-significance absorption<br />

features.<br />

Non-hydrostatic, deep-atmosphere hot Jupiter climate models<br />

Nathan Mayne — University of Exeter!<br />

We present results for the climate of hot Jupiter HD209458b derived using a global<br />

circulation model (GCM) which, using the same numerical scheme, can solve both the full<br />

unsimplified dynamical equations for a rotating atmosphere, as well as including increasing<br />

simplification to these equations. Our results show that the bulk atmospheric flow is largely<br />


obust to the canonical simplifications if short integration times and small vertical domains<br />

are used (i.e. shallow weather layers). However, for longer integrations and models<br />

incorporating a “deeper” (i.e. larger in vertical extent) atmosphere such simplifications to<br />

the dynamical equations produce different flows. We also explore the changes to the<br />

driving, or pumping, mechanisms for the large scale flow features in the atmosphere under<br />

improvements to the dynamical description. We have also adapted a more complete<br />

radiative transfer scheme for the physical conditions of hot Jupiters and I will outline<br />

progress coupling this to the dynamical code.<br />

Chemical disk evolution and element abundances of gas giants<br />

Peter Woitke — St. Andrews University!<br />

We discuss the chemical pre-conditions for planet formation, in terms of gas and ice<br />

abundances as function of time and position in a protoplanetary disk. Considering the<br />

standard core-accretion model for planet formation, the overwhelming majority of the mass<br />

of the gas giant will only be accreted onto the proto-planet in a final rapid run-away phase,<br />

using up the remaining gas in the planet feeding zone. This gas will contain only traces of<br />

refractory elements, and possibly only little amounts of elements like C, N and O, which<br />

may have frozen out as ices before. ProDiMo protoplanetary disk models are used to<br />

predict the chemical evolution of gas and ice in the midplane. We find that cosmic rays<br />

play a crucial role in slowly un-blocking the CO, where the liberated oxygen forms water<br />

which freezes out quickly. Therefore, the carbon-to-oxygen ratio C/O in the gas phase is<br />

found to gradually increase with time in the disk, in a region bracketed by the water and<br />

CO ice-lines. C/O is found to exceed unity after about 7 Myrs, scaling with the cosmic ray<br />

ionization rate assumed.<br />


A radiative-convective equilibrium model for young giant exoplanets: Comparison<br />

with observations and other existing models<br />

Jean-Loup Baudino — LESIA, Observatoire de Paris!<br />

We developed a radiative-convective equilibrium model for young giant exoplanets. Input<br />

parameters are the planet's surface gravity (g), effective temperature (Teff) and elemental<br />

composition. Under the additional assumption of thermochemical equilibrium, the model<br />

predicts the equilibrium temperature profile and mixing ratio profiles of the most important<br />

gases. Opacity sources include the H2-He collision-induced absorption and molecular lines<br />

from H2O, CO, CH4, NH3, VO, TiO, Na and K. Line opacity is modeled using k-correlated<br />

coefficients pre-calculated over a fixed pressure-temperature grid. Absorption by iron and<br />

silicate cloud particles is added above the expected condensation levels with a fixed scale<br />

height and a given optical depth at some reference wavelength. Scattering is not included<br />

at the present stage. Model predictions are compared with the existing photometric<br />


measurements of Planet Beta Pictoris b and Kappa And b in the J, H, Ks, L', NB 4.05, M'<br />

bands and with spectroscopic observations of the HR8799 planetary system to constrain<br />

Teff and g. Finally, our results are compared with those derived from other existing models.<br />

This model will be used to interpret future photometric and spectroscopic observations of<br />

exoplanets with SPHERE, mounted at the VLT with a first light expected in 2014.<br />

Spitzer and z' Secondary Eclipse Observations of the Highly Irradiated Transiting<br />

Brown Dwarf KELT-1b!<br />

Thomas Beatty — Ohio State University!<br />

KELT-1b is a highly-irradiated, highly-inflated, 27 Jupiter-mass object transiting a bright<br />

(V=10.8) F5V star with a period of 1.2 days. KELT-1b offers a unique opportunity to study<br />

the atmosphere of a brown dwarf with known mass, radius, and approximate age, in a<br />

radiation environment similar to hot Jupiters. We present and discuss secondary eclipse<br />

observations of this system taken using the Spitzer Space Telescope and from the ground.<br />

We measure secondary eclipse depths of 0.196+/-0.01% at 3.6 μm and 0.200+/-0.012% at<br />

4.5 μm, corresponding to a fairly grey color of [3.6]-[4.6] = 0.07+/-0.11. Using four separate<br />

ground-based light curves, we find suggestive evidence for the secondary eclipse in the z<br />

band with a depth of 0.046+/-0.023%. These observations represent the first constraints<br />

on the atmospheric dynamics of a highly-irradiated brown dwarf, and are interesting in the<br />

context of both the atmospheres of irradiated giant planets at high surface gravity, and the<br />

atmospheres of brown dwarfs that are dominated by external, rather than internal, energy.<br />

In particular, as compared to objects of similar temperature, KELT-1b has a [3.6]-[4.6] color<br />

that is similar to isolated brown dwarfs, in contrast to lower surface gravity exoplanets,<br />

which tend to have redder colors.<br />

Critically testing atmospheric models with benchmark brown dwarfs<br />

Ben Burningham — University of Hertfordshire<br />

The current generation of wide-field surveys is probing such a volume that significant<br />

numbers of brown dwarfs are being identified as rare wide common proper motion binary<br />

companions to higher mass stellar primaries. If such systems are formed in the same<br />

manner as similarly separated stellar binaries then it follows that the composition and age<br />

of the primary may be used to infer the same properties for the low-mass companion,<br />

making such systems attractive calibrators for substellar and exoplanetary atmospheric<br />

(spectral) model grids. They are thus referred to as benchmark systems. In this<br />

contribution, I will discuss recent results from our search for substellar benchmarks,<br />

focusing on how the emerging grid of calibrated atmospheres can be used to provide new<br />

insights into the strengths and deficiencies of differing model approaches, and highlighting<br />

how benchmark systems have revealed that metallicity is as important as effective<br />

temperature for determining the SED of cool substellar objects. Finally, I will explore how<br />

the potential of benchmark brown dwarfs for breaking observational degeneracies can be<br />

realised to solve key science goals in exoplanetary science.<br />

Doppler imaging of a Nearby Cloudy Brown Dwarf<br />

Ian Crossfield — MPIA<br />

Brown dwarfs provide easily-observable analogues to young extrasolar planets with similar<br />

temperatures and radii but lower masses. Brown dwarfs are the first substellar objects for<br />


which cloud-induced temporal variability has been observed, but so far the<br />

characterization of these complex & dynamic atmospheres has been limited to lowresolution<br />

spectroscopy and photometry. We will present Doppler Imaging of a brown<br />

dwarf’s surface using high-resolution near-infrared spectroscopy. Future such observations<br />

will track the formation, evolution, and breakup of global weather patterns, and will provide<br />

revolutionary new benchmarks against which to compare global circulation models of<br />

cloudy substellar objects.<br />

Ionisation regimes structuring planetary atmospheres!<br />

Christiane Helling — University of St Andrews!<br />

The steady increase of the sample of extrasolar planets broadens our knowledge and at<br />

the same time, reveals our lack of understanding fundamental processes. For example<br />

does the habitability of a planet depend, amongst other things, on how much and which<br />

radiation reached the ground, how clouds form and which effect clouds have on the<br />

composition and on the electric state of the ambient gas from which they form.<br />

We have studied the formation of mineral clouds on planetary atmospheres by a kinetic<br />

approach which allows us to predict the size distribution and material composition of the<br />

cloud particles. These results have been used to study if such clouds can be charged and<br />

under which conditions an electric field breakdown, such as lightning or other transient<br />

luminous events, may occur. Our results suggest that different intra-cloud discharge<br />

processes dominate at different heights inside a cloud, and that the atmospheric volume<br />

affected by large-scale lightening discharges is larger in Brown Dwarfs than in planetary<br />

atmospheres. We demonstrate how different ionisation processes suggest that planets and<br />

brown dwarfs have stratified ionised atmospheres.<br />

Atmospheric cloud models from brown dwarfs to exoplanets<br />

Derek Homeier -- Centre de Recherche Astrophysique de Lyon/ENS-Lyon!<br />

State-of-the-art theoretical models of low-mass stars and brown dwarf atmospheres aim at<br />

a physically and chemically consistent simulation, generally evolving from the assumptions<br />

of hydrostatic and radiative equilibrium as well as a chemical equilibrium composition<br />

based on given input abundances. In further refinement more complex phenomena such<br />

as atmospheric dynamics and departures from chemical equilibrium by advection,<br />

photochemistry or condensate formation can be considered. This approach has allowed<br />

model grids based on a minimal set of parameters to reproduce observed properties of<br />

substellar objects with considerable success. Most important among these is without doubt<br />

the role of cloud opacity throughout the sequence from late-type stars to the coolest brown<br />

dwarfs known to date. I will present the results of the PHOENIX Settling models, which<br />

successfully describe the formation of different cloud types, from iron and silicate dust<br />

dominating in L dwarfs over sulphides and halides that become relevant in cooler T dwarfs,<br />

to the appearance of water ice and colder condensates in the latest Y dwarfs. These<br />

models can often be applied with little modification to lower mass objects such as directly<br />

imaged gas giants, highlighting the effects of lower gravity on atmospheric chemistry and<br />

cloud formation. However, as one explores more fully the domain of exoplanet<br />

atmospheres, increased complexity like global transport triggered by irradition, and<br />

atmospheric chemistry no longer based on scaled-solar compositions come into play.<br />

Consequently the direct retrieval of atmospheric properties from observed data, is often<br />

preferred in these cases, but with only few data points to constrain the models, may<br />

struggle to produce a unique and physically realistic solution. I shall show here how our<br />


models can still be applied in this context to hot Neptunes and super-Earths to place<br />

constraints on atmospheric properties using the most recent transit spectroscopy results.<br />

New insights on beta Pictoris: discovery of two different populations<br />

Flavien Kiefer — Institut d'Astrophysique de Paris!<br />

High-resolution spectroscopic observations of beta Pictoris made with HARPS bring new<br />

information on the exocomets falling onto the star (FEB scenario). With more than a<br />

thousand spectra gathered between 2003 and 2011, we have around 6000 variable<br />

absorptions detected. Using this huge catalogue of events we achieved an unprecedented<br />

statistical and temporal study of beta Pic comets. We will present the results of this<br />

statistial analysis, and display the evidence that allowed us to discover two very different<br />

populations of comets in this young planetary system.<br />

Magnetic fields on L-type brown dwarfs!<br />

Oleksii Kuzmychov — Kiepenheuer-Institut für Sonnenphysik<br />

Several rapidly-rotating L-type dwarfs exhibit transient but periodic radio pulses that are<br />

possibly driven by electron-cyclotron maser (e.g., Hallinan et al. 2007, 2008). For this<br />

mechanism to work, a few kG magnetic field is required. In order to examine whether<br />

these objects possess such a strong magnetic field, we model polarized spectra of L-type<br />

brown dwarfs including transitions in diatomic molecules, such as CrH, FeH, and TiO. We<br />

compare these synthetic spectra with full Stokes spectra of two brown dwarfs measured at<br />

several rotational phases using the low-resolution spectropolarimeter LRIS at the Keck<br />

Observatory in August 2012. We are able to constrain the magnetic field strength in these<br />

objects and discuss implications of our results.<br />

Spectral Retrieval Analysis of the Directly Imaged exoplanets around HR 8799<br />

Jae-Min Lee — University of Zurich<br />

The direct-imaged exoplanets around HR 8799 are photometrically distinct from their<br />

parent star. Spectroscopic measurements along with photometric points between 1 and 5<br />

µm provide vital information on the thermal and chemical structure of the atmosphere,<br />

which have never been achieved from transiting exoplanets. However, it is still mysterious<br />

that the characteristics of the atmosphere show a mixture of brown dwarf and gas giant<br />

features, calling its radius, surface gravity and mass into a question. Here, we perform<br />

inverse modelling by exploiting an optimal estimation retrieval technique and sweep the<br />

parametrized radius and surface gravity space with phenomenological cloud scenarios.<br />

Unlike previous approaches, in which the cloud models are rather sophisticated, we<br />

minimise the number of cloud parameters, e.g., mono-disperse cloud particle size and<br />

optical depth of cloud. We find that the identity of the cloud material gives a non-detectable<br />

effect to our results because the refractive indices of most of materials plausible in this<br />

class of atmosphere are not distinguishable at these wavelengths. Also, we report physical<br />

properties of these planets, such as radius, surface gravity and mass, which can provide<br />

useful constraints for building its formation scenario.<br />


A Comparison of Exoplanet Atmospheric Retrieval Techniques<br />

Michael Line!— University of California Santa Cruz<br />

Secondary eclipse spectra allow us to infer the temperatures and compositions of<br />

exoplanet atmospheres. A variety of statistical approaches exist to determine the most<br />

probable set of temperatures and compositions such as Markov Chain Monte Carlo and<br />

Optimal Estimation. I will give an overview of these approaches in the context of the<br />

Bayesian formalism and discuss the similarities and differences in their derived posterior<br />

probabilities. I will show in which regimes optimal estimation is appropriate and in which<br />

regimes MCMC approaches are necessary. Finally, as a side, I will discuss the potential<br />

pitfalls of statistical determinations of the atmospheric C/O ratio.<br />

Young and Planetary-Mass: Connecting Low-Gravity Field Brown Dwarfs and<br />

Directly Imaged Gas-Giant Planets!<br />

Michael Liu — University of Hawaii, Institute for Astronomy!<br />

Direct detections of young gas-giant exoplanets and recent identification of very young<br />

field brown dwarfs are strengthening the observational link between the exoplanet and<br />

brown dwarf populations, enriching our understanding of both classes of objects. However,<br />

studies to date have typically focused on individual discoveries. We present a large<br />

comprehensive study of the youngest field brown dwarfs, comprising both previously<br />

known objects and our new discoveries from the Pan-STARRS-1 wide-field survey. These<br />

objects have physical properties that overlap young gas-giant planets and thus are<br />

promising analogs for studying exoplanet atmospheres at high S/N and spectral resolution<br />

down to ~5 Jupiter masses. We combine high-quality spectra and parallaxes to study their<br />

spectral energy distributions, luminosities, temperatures and ages. We demonstrate that<br />

the peculiar IR colors and magnitudes of the planets around 2MASS J1207-39 and HR<br />

8799 do occur in some young brown dwarfs, but these properties do not have a simple<br />

correspondance with age. We find that young field brown dwarfs can have unusally low<br />

temperatures (but they are not underluminous, as often claimed). To help provide a<br />

reference for upcoming extreme-contrast imaging surveys, we establish a grid of spectral<br />

standards and benchmarks, based on membership in nearby young moving groups, in<br />

order to calibrate gravity (age) and temperature diagnostics in near-IR spectroscopy.<br />

Finally, we use our data to critically examine the possibility that free-floating objects and<br />

companions may share different evolutionary histories, thereby complicating the "brown<br />

dwarf-exoplanet connection”.<br />

MagAO/VisAO Optical Imaging of beta Pictoris b: A Comparative Study of<br />

Exoplanets and Brown Dwarfs!<br />

Jared! Males — University of Arizona<br />

We used the Magellan AO system's visible wavelength diffraction limited camera, VisAO,<br />

to image the ~10 Jupiter mass exoplanet beta Pictoris b. This is the first ground-based<br />

direct image of an exoplanet at wavelengths less than 1 micron. Using our photometry,<br />

combined with existing JHK measurements, we compare beta Pic b to field brown dwarf<br />

spectra. Our analysis yields a rigorous empirical determination of the planet's spectral<br />

type, and through this an estimate of effective temperature. Our photometry highlights the<br />

extreme diversity amongst the directly imaged extrasolar giant planets and both field and<br />

companion brown dwarfs, yet points to remarkable similarities in formation and evolution<br />

despite this diversity.<br />


Comprehensive Results from the Weather on Other Worlds Spitzer Campaign:<br />

Photometric Variability Is Ubiquitous on L and T Dwarfs<br />

Stanimir Metchev — Western University!<br />

I will present the first comprehensive results from the ""Weather on Other Worlds"" Spitzer<br />

Exploration Science program: the most precise and comprehensive study of cloud-induced<br />

photometric variability in L and T dwarfs. We observe that 45% of L3-T8 dwarfs are<br />

variable, with amplitudes between 0.2%-5% at 3.6 and 4.5 micron. Contrary to<br />

expectations, the variability fraction is independent of spectral type, suggesting that cloud<br />

phenomena are present in ultra-cool dwarfs over the entire 700-2000 K effective<br />

temperature range surveyed in our program, and likely at even cooler temperatures.<br />

Combined with spin-axis and cloud/hole viewing geometry considerations, our findings<br />

indicate that cloud-induced variability is present on virtually all L3-T8 dwarfs. If the<br />

detected variability is caused by single large storms, rather than by multiple smaller ones,<br />

the measured amplitudes and temperature contrasts indicate that these features cover<br />

between 8%-40% of the visible disks of brown dwarfs. That is, atmospheric storms with<br />

sizes between approximately half to twice that of the Great Red Spot on Jupiter are<br />

ubiquitous on 700-2000 K brown dwarfs.<br />

Water Clouds in Y Dwarfs and Exoplanets!<br />

Caroline Morley — University of California Santa Cruz!<br />

A major frontier in the fields of directly imaged planets is finding and characterizing the<br />

coolest known objects. For planets with effective temperatures below about 450 K, it has<br />

long been known that water clouds will form and shape the infrared spectra of these<br />

objects. However, no previous modeling studies have systematically shown the effect that<br />

water clouds will have on the spectra of these cold planetary-mass objects. Within 1-2<br />

years, GPI and SPHERE will be able to directly image and characterize planets down to<br />

~300 K, so the time is right to better understand cool atmospheres dominated by water<br />

clouds.<br />

Cold brown dwarfs will also contain water clouds and they provide a test-bed for our new<br />

generation of cloudy atmosphere models. The newly-proposed spectral type Y includes<br />

brown dwarfs cooler than about 500 K, many of which will have water clouds. Over a<br />

dozen Y dwarfs have now been discovered and are beginning to be characterized;<br />

followup studies by various groups aim to measure their spectra, monitor them for<br />

variability, and measure their parallaxes. The models presented here will allow us to<br />

determine the physical properties of the Y dwarfs and allow us to compare the brown dwarf<br />

population to directly-imaged planets as they are discovered.<br />

Here we present a study of clouds in objects that bridge the gap between brown dwarfs<br />

and solar-system planets, with effective temperatures from 200 to 500 K. We present<br />

results for both planetary-mass objects and for Y dwarfs and compare models to available<br />

Y dwarf spectra to test their validity. We make predictions for the spectra, colors, and<br />

magnitudes of young giant planets and the Y dwarf population. We also predict the level of<br />

variability expected in the near- and mid-infrared.<br />

Direct imaging of exoplanets: Remote sensing of planetary systems and processes<br />

Katie Morzinski — University of Arizona!<br />

Beta Pictoris hosts a planet at sub-arcsecond separation, detected via high-contrast<br />

imaging. We observed Beta Pic b at first-light of the new Magellan adaptive optics<br />


instrument "MagAO" in December 2012, simultaneously with our visible-light and infrared<br />

cameras. I will present my MagAO imaging data of Beta Pic b at 5 passbands, providing a<br />

fuller picture of the planet's spectral energy distribution. This broad wavelength coverage<br />

will be crucial to determining the energy balance of new exoplanets as improved AO<br />

technology allows direct imaging to probe closer separations and lower masses. MagAO is<br />

unique in achieving diffraction-limited imaging from 0.6-5 microns, and will be vital to<br />

characterizing these planetary systems.<br />

The Mid-Infrared Properties of Directly-Imaged Exoplanets<br />

Andrew Skemer — University of Arizona!<br />

Self-luminous exoplanets emit the majority of their photons in the mid-infrared (>3 micron).<br />

However, the difficulty of working in the thermal infrared from the ground has precluded the<br />

detailed studies of exoplanets at these longer wavelengths.<br />

Using the low-emissivity adaptive optics systems at the LBT and Magellan, we present 6<br />

new photometric points on the HR 8799 planets and 1 new photometric point on 2M1207<br />

b. These data probe the 3-4 micron region where previous studies have found a 1-2<br />

magnitude discrepancy between their atmospheres and field brown dwarfs. For the HR<br />

8799 planets, we find a shallow 3-4 micron slope with only a hint of possible absorption in<br />

the methane 3.3 micron fundamental absorption band (possibly indicating the presence of<br />

patchy clouds). For 2M1207 b we find a similar if more extreme behavior, with no sign of<br />

methane absorption.<br />

The study has implications for understanding the broad properties of extrasolar giant<br />

planets, and suggests that future mid-infrared direct-imaging searches (particularly JWST)<br />

may need to reconsider their search strategy.<br />

A large near-IR photometric monitoring survey of 69 ultracool L &T brown dwarfs<br />

Paul Anthony!Wilson — University of Exeter<br />

As the brown dwarf atmosphere cools through the L-T spectral sequence a rapid shift from<br />

the red to the blue colours are observed across the L-T type transition. This shift in colour<br />

happens across a narrow effective temperature range, which is hard for 1-D atmosphere<br />

models to currently reproduce. Patchy clouds might be the explanation of the rapid change<br />

in colour observed over a narrow temperature range. The consequence of patchy clouds<br />

would be variations in the observed flux due to the rotation and evolution of the clouds.<br />

I will present the results from our large near-IR photometric monitoring campaign which<br />

covers 69 ultracool L & T type brown dwarfs. In particular I will discuss the frequency and<br />

amplitude of variability across the different spectral types highlighting that our survey finds<br />

new large amplitude variables across the L - T spectral range showing no preference for<br />

the transition. I will also talk about observing variability at the much cooler T-Y transition.<br />


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© Rough Guides / Map published on http://Switzerland.isyours.com<br />

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The conference was organised with the<br />

support of the University of Exeter<br />


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