Planete, the planet formation model of Bern. 9 gas disk. Courtesy of Y. Alibert cf. Alibert et al. (2013) and references therein ...
Composition of disks and planets A. Thiabaud - U. Marboeuf - Y. Alibert - N. Cabral K. Mezger - I. Leya
1
Exoplanets First discovery Mayor & Queloz (1995, Univ. of Geneva) 51 Pegasi b @ 4,8.1014 km, M=0.5 MJupiter, R=1.3 RJupiter Space missions Kepler, COROT, HST, etc ...
Credit NASA
2
Main methods of Detection Radial Velocity Measurement of M.sin(i), period, eccentricity.
3
Main methods of Detection Radial Velocity Measurement of M.sin(i), period, eccentricity.
3
Main methods of Detection (2) Transit Measurement of radius.
4
Why do we study the composition? Observational data • Provides estimates for mass and radius => mean density. • Gas composition only! No real constraint on the solids.
• • • •
Study the composition Constraints on the solid part of the planet. Exact composition of the planet => true density. If true mass is known, then true radius becomes available and inversely. Composition of the atmosphere: habitable planets?
Space missions to characterize exoplanets • CHEOPS (CHaracterising ExOPlanet Satellite): get transits of planets already detected by RV => precise measurement of radius, best estimate of mass => bulk density. • TESS (Transiting Exoplanet Survey Satellite)
5
The Habitable Zone Circumstellar Habitable Zone = region around a star within which planets with Earth-like atmosphere can support liquid water at their surface.
Credits: https://www.e-education.psu.edu
6
Take home message #1 Studying exoplanets and their composition enables to:
BETTER UNDERSTAND THE FORMATION OF PLANETS. SEARCH FOR HABITABLE WORLD.
7
Stellar and planetary formation in a nutshell
8
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk
9
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk accretion
9
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk
mass
100 Mearth
10 Mearth
1 Myr
2 Myr 3 Myr
time
9
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk excitation
9
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk excitation
gas drag
9
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk excitation
gas drag
9
gas drag
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk excitation
ang. momentum exchange eccentricity damping
ang. momentum exchange eccentricity damping
9
gas drag
gas drag
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern gas disk excitation
grav. interactions ang. momentum exchange eccentricity damping
ang. momentum exchange eccentricity damping
9
gas drag
gas drag
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern Disk truncation by magnetic field
gas disk excitation
grav. interactions ang. momentum exchange eccentricity damping
ang. momentum exchange eccentricity damping
9
gas drag
gas drag
cf. Alibert et al. (2013) and references therein
Courtesy of Y. Alibert
Planete, the planet formation model of Bern Disk truncation by magnetic field
gas disk excitation
grav. interactions ang. momentum exchange eccentricity damping
ang. momentum exchange eccentricity damping
Irradiation 9
gas drag
gas drag
Take home message #2
DISKS AND PLANETS HAVE A COMPOSITION MATCHING THE COMPOSITION OF THE HOST STAR.
10
Compositions in the Solar System in wt%
Fe O Mg Al Si Ca Others
70 53 35 18 0 After Morgan & Anders (1980) 11
Compositions in the Solar System (2) H He Others
Gas composition only!
in wt%
100 75 50 25 0
12
Models predict ices on surface
Chemical definitions
Refractory molecules Molecules that condense at temperature higher than the condensation temperature of the water (≳170K @ 10-4 Pa) : Silicates, oxides... Volatile molecules Molecules that condense at temperature lower (or equal) than the condensation temperature of the water : CO, CO2, CH4, CH3OH
13
The condensation sequence
Brearley (1998) 14
Ice- and Refractory-lines No irradiation
Irradiation
No irradiation, higher disk mass 15
1 AU = mean distance Earth-Sun
Results of our simulations Thiabaud, Marboeuf, Alibert et al. (2014)
No irradiation
1 AU = mean distance Earth-Sun
16
Results of our simulations (2) Thiabaud, Marboeuf, Alibert et al. (2014)
Irradiation
1 AU = mean distance Earth-Sun
17
Take home message #3
3 BIG TYPES OF PLANETS CAN BE FORMED: Rocky (Terrestrial) Gas Giants Icy planets WE FORM IN THE SIMULATIONS THESE 3 TYPES AT EXPECTED LOCATIONS AND MASSES
18
Conclusions • The number of exoplanets detected keeps growing! To date, more than 1000. • The method to detect exoplanets are various, can be done by ground or space observations, and give estimates for different variables. • Discs and planets have a composition that results from the stellar formation. • A lot of processes need to be taken into account for planetary formation simulations. • Different type of planets can be formed event though the initial parameters (abundances, ...) are the same. • In our simulations, we can reproduce all planets of the solar system as they are described to date. • The irradiation and the mass of the disk move the position of every lines, especially the ice-line, thus forming more or less rocky planets (expected). 19
Future work • Composition of the gas accreted + pollution of the atmosphere, cf next talk. So far ONLY THE BULK COMPOSITION IS COMPUTED and the gas is supposed to be H2+He. But we know from observations (+ planets of Solar System) that the gas is not only H2+He. • Realistic migration of planetesimals. • Important elements. • Other models for planetary formation (Ida & Lin’s....).
Even though our simulations match pretty well the expectations, there is still a lot of work to do!
20
THANK YOU!
21
Temperature profiles
22
