Probabilistic Constraints on the Mass and Composition of Proxima b

• Main Authors: Bixel, Alex, Apai, Dániel
• Other Authors: Univ Arizona, Dept Planetary Sci, Lunar & Planetary Lab
• Language: en
• Published: IOP PUBLISHING LTD 2017
• Subjects: planets and satellites: composition; planets and satellites: individual ( Proxima Centauri b); methods: numerical; methods: statistical
• Online Access: http://hdl.handle.net/10150/623234; http://arizona.openrepository.com/arizona/handle/10150/623234

Recent studies regarding the habitability, observability, and possible orbital evolution of the indirectly detected exoplanet Proxima b have mostly assumed a planet with M similar to 1.3 M-circle plus, a rocky composition, and an Earth-like atmosphere or none at all. In order to assess these assumptions, we use previous studies of the radii, masses, and compositions of super-Earth exoplanets to probabilistically constrain the mass and radius of Proxima. b, assuming an isotropic inclination probability distribution. We find it is similar to 90% likely that the planet's density is consistent with a rocky composition; conversely, it is at least 10% likely that the planet has a significant amount of ice or an H/He envelope. If the planet does have a rocky composition, then we find expectation values and 95% confidence intervals of < M >(rocky) = 1.63(-0.72)(+1.66) M-circle plus for its mass and < R >(rocky) = 1.07(-0.31)(+0.38) R-circle plus for its radius.