Year: 2015
Type: article
Abstract: Knowledge of both the mass and radius of an exoplanet allows us to estimate its mean density, and therefore its composition. Exoplanets seem to fill a very large parameter space in terms of mass and composition, and unlike the solar-system's planets, exoplanets also have intermediate masses (∼5–50 ) with various densities. In this Letter, we investigate the behavior of the mass–radius relation for methane (CH 4 ) planets and show that when methane planets are massive enough ( 15 M ), the methane can dissociate and lead to a differentiated planet with a carbon core, a methane envelope, and a hydrogen atmosphere. The contribution of a rocky core to the behavior of a CH 4 planet is also considered. We also develop interior models for several detected intermediate-mass planets that could, in principle, be methane/methane-rich planets. The example of methane planets emphasizes the complexity of the mass–radius relation and the challenge involved in uniquely inferring the planetary composition.
Authors: Ravit Helled, Morris Podolak, Eran Vos
Institution: Tel Aviv University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2196674287