Probabilistic Constraints on the Mass and Composition of Proxima b

Alex Bixel, Dániel Apai

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Recent studies regarding the habitability, observability, and possible orbital evolution of the indirectly detected exoplanet Proxima b have mostly assumed a planet with M ∼ 1.3 M , 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 ∼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 for its mass and R for its radius.

Original languageEnglish (US)
Article numberL31
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Feb 20 2017


  • methods: numerical
  • methods: statistical
  • planets and satellites: composition
  • planets and satellites: individual (Proxima Centauri b)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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