EVOLUTIONARY MODELS of SUPER-EARTHS and MINI-NEPTUNES INCORPORATING COOLING and MASS LOSS

Alex R. Howe, Adam S. Burrows

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

We construct models of the structural evolution of super-Earth- and mini-Neptune-type exoplanets with H2-He envelopes, incorporating radiative cooling and XUV-driven mass loss. We conduct a parameter study of these models, focusing on initial mass, radius, and envelope mass fractions, as well as orbital distance, metallicity, and the specific prescription for mass loss. From these calculations, we investigate how the observed masses and radii of exoplanets today relate to the distribution of their initial conditions. Orbital distance and the initial envelope mass fraction are the most important factors determining planetary evolution, particularly radius evolution. Initial mass also becomes important below a "turnoff mass," which varies with orbital distance, with mass-radius curves being approximately flat for higher masses. Initial radius is the least important parameter we study, with very little difference between the hot start and cold start limits after an age of 100 Myr. Model sets with no mass loss fail to produce results consistent with observations, but a plausible range of mass-loss scenarios is allowed. In addition, we present scenarios for the formation of the Kepler-11 planets. Our best fit to observations of Kepler-11b and Kepler-11c involves formation beyond the snow line, after which they moved inward, circularized, and underwent a reduced degree of mass loss.

Original languageEnglish (US)
Article number150
JournalAstrophysical Journal
Volume808
Issue number2
DOIs
StatePublished - Aug 1 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • planetary systems
  • planets and satellites: atmospheres
  • planets and satellites: composition
  • planets and satellites: interiors
  • planets and satellites: physical evolution

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