HOW ROCKY ARE THEY? THE COMPOSITION DISTRIBUTION OF KEPLER'S SUB-NEPTUNE PLANET CANDIDATES WITHIN 0.15 AU

Angie Wolfgang, Eric Lopez

Research output: Contribution to journalArticle

99 Scopus citations

Abstract

The Kepler Mission has found thousands of planetary candidates with radii between 1 and 4 R. These planets have no analogues in our own solar system, providing an unprecedented opportunity to understand the range and distribution of planetary compositions allowed by planet formation and evolution. A precise mass measurement is usually required to constrain the possible composition of an individual super-Earth-sized planet, but these measurements are difficult and expensive to make for the majority of Kepler planet candidates (PCs). Fortunately, adopting a statistical approach helps us to address this question without them. In particular, we apply hierarchical Bayesian modeling to a subsample of Kepler PCs that is complete for P < 25 days and Rp1 > 1.2 R and draw upon interior structure models that yield radii largely independent of mass by accounting for the thermal evolution of a gaseous envelope around a rocky core. Assuming the envelope is dominated by hydrogen and helium, we present the current-day composition distribution of the sub-Neptune-sized planet population and find that H+He envelopes are most likely to be ∼1% of these planets' total masses with an intrinsic scatter of ±0.5 dex. We address the gaseous/rocky transition and illustrate how our results do not result in a one-to-one relationship between mass and radius for this sub-Neptune population; accordingly, dynamical studies that wish to use Kepler data must adopt a probabilistic approach to accurately represent the range of possible masses at a given radius.

Original languageEnglish (US)
Article number183
JournalAstrophysical Journal
Volume806
Issue number2
DOIs
StatePublished - Jun 20 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'HOW ROCKY ARE THEY? THE COMPOSITION DISTRIBUTION OF KEPLER'S SUB-NEPTUNE PLANET CANDIDATES WITHIN 0.15 AU'. Together they form a unique fingerprint.

  • Cite this