Ranges of atmospheric mass and composition of super-earth exoplanets

Research output: Contribution to journalArticle

104 Scopus citations

Abstract

Terrestrial-like exoplanets may obtain atmospheres from three primary sources: capture of nebular gases, degassing during accretion, and degassing from subsequent tectonic activity. Here we model degassing during accretion to estimate the range of atmospheric mass and composition on exoplanets ranging from 1 to 30 Earth masses. We use bulk compositions drawn from primitive and differentiated meteorite compositions. Degassing alone can create a wide range of masses of planetary atmospheres, ranging from less than 1 % of the planet's total mass up to ∼6 percent by mass (mass%) of hydrogen, ∼20 mass% of water, and/or ∼5 mass% of carbon compounds. Hydrogen-rich atmospheres can be outgassed as a result of oxidizing metallic iron with water, and excess water and carbon can produce atmospheres through simple degassing. As a byproduct of our atmospheric outgassing models we find that modest initial water contents (10 mass% of the planet and above) create planets with deep surface liquid water oceans soon after accretion is complete.

Original languageEnglish (US)
Pages (from-to)1237-1246
Number of pages10
JournalAstrophysical Journal
Volume685
Issue number2
DOIs
StatePublished - Oct 1 2008

Keywords

  • Accretion, accretion disks
  • Planets and satellites: formation
  • Solar system: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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