Comparison with extrasolar planets
Composition of exoplanets
What are exoplanets made of? What is the probability of an exoplanet to be Earth-like? What are the controlling parameters for the diversity in planet structure?
In order to tackle these and other questions, we use Bayesian inference analysis to quantify confidence regions of interior parameters.
The data are few and dat errors are large. In addition, there are different interior structures that cannot be distinguished by observable data. Thus, interior parameters are highly degenerate. In order to make a meaningful statement about interiors of exoplanets, we quantify parameter degeneracy.
- Dorn, Caroline; Venturini, Julia; Khan, Amir; Heng, Kevin; Alibert, Yann; Helled, Ravit; Rivoldini, Attilio; Benz, Willy (2016):
A Generalized Bayesian Inference Method for Constraining the Interiors of Super Earths and Sub-Neptunes. A&A, (accepted)
- Dorn, Caroline; Hinkel, Natalie R.; Venturini, Julia (2016):
Bayesian analysis of interiors of HD 219134b, Kepler-10b, Kepler-93b, CoRoT-7b, 55 Cnc e, and HD 97658b using stellar abundance proxies. A&A, (accepted)
- Dorn, Caroline; Khan, Amir; Heng, Kevin; Connolly, James A. D.; Alibert, Yann; Benz, Willy; Tackley, Paul (2015):
Can we constrain the interior structure of rocky exoplanets from mass and radius measurements?. A&A, 577, A83
Statistical comparison with population synthesis
The steadily growing population of exoplanets yields numerous statistical constraints that are of high importance for theoretical planet formation models. This includes distributions of the mass, the semi-major axis, the eccentricity, the radius and the luminosity, their mutual dependencies, as well as correlations with stellar properties like the metallicity. Particularly strong observational constraints can be obtained when the theoretical predictions of planetary population syntheses are compared with many different observational techniques. The planetary mass function can for example be compared with the results of radial velocity surveys, while the plot below shows for a synthetic population around solar-like stars the predicted contrasts in the H-band that can be compared with direct imaging surveys like NACO, GPI, or SPHERE. The plot also shows the C/O ratio predicted by our chemistry model. The C/O strongly affects the abundances of spectroscopically active molecules like CO, H2O, CH4 or CO2 and bears an imprint of the formation history and location of an exoplanet, at least if the atmospheric composition is representative of the bulk composition. This is shown in the plot by the size of a point that represents the distance from the star where the planet reaches the cross-over mass. Such combined constrains are important observational checks for the internal coherence of theoretical formation models.
- Benz, Willy; Ida, Shigeru; Alibert, Yann; Lin, Douglas; Mordasini, Christoph (2014):
Planet Population Synthesis. Protostars and Planets VI, 691
- Mordasini, Christoph; Alibert, Yann; Benz, Willy; Naef, Dominique (2009):
Extrasolar planet population synthesis. II. Statistical comparison with observations. A&A, vol. 501, pp. 1161