Comet Siding Spring Passes Mars
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Extrasolar Planets = 889

Comet Siding SpringPasses Mars• From Earth and Mars ReconOrbiter

MigratingPlanets• Planets encounteringplanetesimals sweep/ejectplanetesimals into asteroidbelt, Kuiper belt, Oort cloud• Move Jovian planets out/independing on if they pass infront or behind planet

Planetary Migration• Jupiter and Saturn may have formedmuch further from Sun & moved in• Uranus and Neptune moved furtherout from Sun

Fragmentation• High speed collisions betweenprotoplanets & planetesimalscreates a debris disk• P/2010A2 comet? P/2013R3?Collision of 2 small asteroids?

Debris Disk• Not the dense protoplanetarydisks that form planets• Cold debris disks are left• Made from asteroid, comet,planetesimal collisionsβ Pic diskin CO fromALMA

Large Impacts• In final stages a planet wouldhave had many collisions withbodies the size of planets• Such impacts could tilt axis ofrotation of Uranus & nearly stoprotation of Venus• Solar system is like a full coffeecup – some coffee probably gotspilled

Processes ThatCleared theInner SolarSystem• Radiation pressure from sun&stars• Protosun’s wind (&stellar) blowsaway gas & dust• Planetesimals incorporated intoplanets or ejected• All done in millions of years

Planets1. Orbit the Sun =Not moon of some planet2. Spherical3. Have cleared own orbit. IAU 2006

NewPlutoDebate• New Horizons Probe Jan 2006• Gareth Williams: IAU MPC, not planet, many morelike Pluto• Owen Gingerich: Harvard Historian, planet isculturally defined, IAU should define subdivisons• Dimitar Sasselov: the director of Harvard’splanetary program, “orbits Sun” does not include,free floating or Extrasolar Planets.

Extrasolar Planets (1832)• = Planets orbiting stars other than the sun• Planets are less than 13Jupiters =Brown Dwarf• Planets will be a billion times fainter and• Within the seeing disk of stars seen from Earth

Zeroth: Astrometric Detection (2)• Stellar motions around Centre of Mass not resolved=too small to be measured• First detection = Gl 876 announced 2002• Previously known planet from radial velocity studies

First Method:Timing(16)• First planets discovered• By Wolszczan in 1989• Would have been insidesupernova explosion• 3 pulsar systems/3&1&1 planets

The linked image cannot be displayed. The file may have been moved, renamed, or deleted. Verify that the link points to the correct file and location.2nd Method: Direct Imagingof Extrasolar Planets (51)• Planets are billions times fainter than star• Usually not resolved from star

Third: GravitationalMicrolensing (32)• Foreground star & planet lensesbackground star=microlensing• One planet=5.5 Earth masses• Frequency of planets likely90% for M dwarfs• Predicted by R. Nemiroff

The first planetdiscovered in thesolar neighborhoodin 1995Fourth: Radial Velocity (577)• Star pulled back & forth around Centerof Mass by planet’s gravity• Doppler shift measures velocity of star• Technique pioneered at DAO, UBC,UVic by Walker, Campbell and Yang

Fifth: Planetary Transits• 1151 planets, 632systems, 352multiples• Planet crosses in between Earth and star and wesee a decrease in brightness ~1.7%• Observations by Deeg and Garrido at the 0.9mSierra Nevada Telescope.Bill Borucki

Kepler Satellite• Launched 06Mar09• Into Earth trailing orbit• Surveying 150,000 stars• Found 3601 candidates:• 55 Super-Jupiter sized• 203 Jupiters&1181 Neptunes• 680 Super-Earth& 207 Earths• Marcy et al. use Keck forRadial Velocity confirmation• Not dead due to reaction wheel

The least productive method ofextrasolar planet hunting is:a) Astrometry = star’s position variationsb) Direct imaging = adaptive opticsc) Microlensing = light focused by gravityd) Radial Velocity = star orbits centre of masse) Transits = brightness variations = eclipses

Partial Solar Eclipse• Start 1:32• Mid 2:58• End 4:17PDT• On roof of BobWright Centre

ExtrasolarPlanets• 1832 extrasolar planets• 1145systems, 469multipleplanet systems• Orbiting stars, Binaries• Giants, White Dwarfs• Radial Velocity, Transits,Microlensing, Imaging• Hot Jupiters = Jupitersized Planets orbiting closeto their star

Selection Effects• Easier to detect massive planets close to their stars =Hot Jupiters rather than Super-Earths or Earths• Big Planet=Big velocity variations & Deep transits• Close=Short Periods. Orbit inclination not as critical

Transit False AlarmProbabilities• 715 new extrasolar planetsannounced in Feb 2014

Multiple Planets• A system with multiple planets is stable BUT notwith multiple stars mixed in• Gravitational interaction gives mass of planets

Mass of Extrasolar Planets• The more massive the planet the more the star moves• Radial velocity variations depend on inclination oforbit

Transit DepthGives Size ofPlanet• Big planet deeptransit• Small star deeptransit

Density ofPlanets• Radial Velocity methodfinds minimum mass• Transits give inclination+Radial Velocity=true mass• Transits give diameterthus Density ècomposition

Temperatureof Planet• Planets only a milliontimes fainter in Infrared• Using the Spitzer IRtelescope the planet’seclipse can be seen• Gives planet temp=770K• Drawn in Visible and IR

Atmosphere of a Planet• During planet’s transit the star’s light goes thru atmosphere• Can see the planet’s atmosphere in absorption• Hydrogen, Na, H 2 O gas in atmosphere; blown away bystellar wind

Water in Planet’sAtmospheres• Absorption featuresfrom light passingthru planet’satmosphere duringtransits• Model / Observations• Some planets havefeatureless spectra??Clouds? Of??

The linked image cannot be displayed. The file may have been moved, renamed,Atmosphereor deleted. Verify that the link points to the correct file and location.ofTransiting Planets• Planets which transit will also be eclipsed• If you subtract an eclipse spectrum froman out of eclipse spectrum you get theplanet’s spectrum• Look for “bio-markers” (CH 4 +O 2 )

Map of Extrasolar Planet• Planet orbits HD189733 showingphases, assuming locked in rotation• Winds transport heat to night side• Map has temperatures of 650-900C

Exoplanets inRetrograde Orbits• As the planet transits, it covers thered or blue shifted side of the star:shows rotation of star/planetRetrogradePrograde

Kepler-56• Has 2 planets not in equatorial plane of star• Companion star pulls on planets & misaligns them

Habitable Zone• Surface temperatureallows liquid water• Star’s temperaturedetermines distancefrom star and width• Modified byatmosphere

Tatooine twice• Kepler16 first circumbinaryplanet; distance=200light years• Orbital period=229days; 0.3M J ;0.22R J ; Temp=-80C• Kepler 47 in habitable zone

New Extrasolar Planet• Swiss team finds planet orbiting α Centauri B• Closest star = 4.3 light years; triple system• Centarus A&B separated by ~Sun-Uranus distance• ~Earth mass but period 3.26days = too close & hot

Most Earth-like Planet• Of 1800 confirmed planets, 10 are in habitable zone

An Earthlike Planet?• Gliese 581d? Or g if it exists• Close to M dwarf star; tidally locked• Sunlight redistributed by winds?• Message was sent 09OCT2008• 20 light years distant so reply in 2048

The density of an extrasolar planet:a. Is the mass of the planet divided by its volume.b. Is measured by observing the radial velocityvariations and the depth of the transit.c. Allows us to make some educated guesses as tothe composition of planets.d. Ranges from less than Saturn ~1gm/cm 3 to morethan Earth 5.5gm/cm 3e. All of the above

The habitable zone:a. Is where we find habitsb. Is the area surrounding a star wherewe might find liquid waterc. Is where we find inhabitantsd. Is where we have found alien lifee. All of the above

Free-floating Planet• Part of AB Doradus moving group givesage=400million yr & distance=100ly• IR color & spectra give temperature=430K• Escaped from star or born from small dust cloud?• How many of these are there???

Most Earthlike Planet = Kepler 62e,f• Kepler 62 smaller cooler star Apr 2013• No masses yet but radii of 1.4 &1.6 Earths• So terrestrial planets in habitable zone (liquid H 2 O

HR8799c, C. Marois, HIA, Victoria• 30million year old star in Pegasus with debris disk• 4 planets with observed orbital periods 50-500years• Spectra show c has H 2 O, CO, CH 4

Planet-Hunters Find Planet• Amateur/Professional online group examines• Light curves of Kepler stars for transits• Found planet in eclipsing binary system withdistant binary in system = quadruple star

WASP-12b• Jupiter mass but twice the radius• Very low density• Very close to star = very hot and strong tides• Will last only ~10million years

HAT-P-7 b• First Kepler data• Shows Eclipse,Occultation, Phases• No Earth typeplanets; yet

• Discovered by CoRoT2009• Transit is 0.00035 deepso diameter ~2Earths• Radial Velocity =>~8Earth Masses• Orbital Period~20hoursSmallest Exoplanet

Planets / Metal Abundance2P planet ~ ( NFe/ NH)

Extrasolar Planets• Nature of Things• Thursday 15Nov 8pm

Upsilon Andromedae System

The Planet Detection Techniques

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