Exoclimes_Conference_booklet1

carbon- and oxygen-bearing species. We present ground-based high-resolution spectra
from CRIRES/VLT at 3.2 microns of several transiting and non-transiting hot Jupiter
atmospheres (51 Peg b, Tau Boo b, and HD 209458 b), in which we have searched for the
radial velocity signature of water, methane and carbon dioxide molecules in the planetary
atmospheres. We compare the results of our search with the detections of CO already
reported in these hot Jupiter atmospheres, and discuss their temperature-pressure profiles
and relative abundance ratios. Preliminary results indicate a significant abundance of
water in 51 Peg b, consistent with tentative reports of water at 2.3 microns.
Observation of Magnesium : A new Probe of Exoplanets' Thermospheres and
Exopheres!
Vincent Bourrier — Institut d'Astrophysique de Paris
Transit observations of HD209458b in the UV revealed signatures of neutral magnesium
escaping the planet upper atmosphere. The absorption detected in the MgI line arises from
the transition region between the thermosphere and the exosphere, and provides
unprecedented information on the physical conditions at the altitude where atmospheric
escape takes place. These observations have been interpreted using a 3D particle model
coupled with an analytical modeling of the atmosphere below the exobase. Thus we
estimated the planetary wind velocity and the exobase altitude, and also obtained an new
estimate of the atmospheric escape rate. More generally, we show that magnesium
absorption lines provide a powerful tool to study the upper part of exoplanets'
atmospheres. We identified a dozen of exoplanets with host stars bright enough for their
atmosphere to be observed using the magnesium lines.
Probing the atmospheres of non-transiting exoplanets: CO and H2O absorbtion in
HD179949b!
Matteo Brogi! — Leiden Observatory
In recent years, ground-based high-resolution spectroscopy has become a powerful
method for studying exoplanet atmospheres. It is capable to robustly identify molecular
species via line matching, and to detect the radial velocity of the planet itself. Moreover, by
targeting the planet thermal emission directly, it does not require the planet to transit.
Thanks to this method, the mass and orbital inclination of non-transiting planets can be
determined and their atmospheric composition studied.
I will present our latest K-band observations of HD179949b with CRIRES at R=100,000.
We detect an absorption signal from water vapour and carbon monoxide at SNR=6.5,
meaning that the portion of the planet’s atmosphere probed by these observations does
not have an inversion layer. The derived mass and orbital inclination for the planet are
(0.98+/-0.04) Jupiter masses and (68+/-4) degrees respectively.
Except for young, self-luminous directly-imaged planets, only high-resolution
spectroscopy currently allows the atmospheric characterization of non transiting planets.
With the next generation of ELTs and this technique, a complete census of this class of
bodies will be possible, revealing for the first time their properties and actual mass
distribution.
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