Composition of Terrestrial Exoplanet Atmospheres from Meteorite Outgassing Experiments

Abstract

Terrestrial exoplanets likely form initial atmospheres through outgassing during and after accretion, although there is currently no first-principles understanding of how to connect a planet's bulk composition to its early atmospheric properties. Important insights into this connection can be gained by assaying meteorites, representative samples of planetary building blocks. We perform laboratory outgassing experiments that use a mass spectrometer to measure the abundances of volatiles released when meteorite samples are heated to 1200 ${}^{\circ }$C. We find that outgassing from three carbonaceous chondrite samples consistently produce H${}_2$O-rich (averaged ~66 %) atmospheres but with significant amounts of CO (~18 %) and CO${}_2$ (~15 %) as well as smaller quantities of H${}_2$ and H${}_2$S (up to 1 %). These results provide experimental constraints on the initial chemical composition in theoretical models of terrestrial planet atmospheres, supplying abundances for principal gas species as a function of temperature.

42 pages, 9 Figures, 2 Tables, 4 Supplementary Figures, 3 Supplementary Tables, published in Nature Astronomy (2021)

References in corpus (4)

• The Atmospheric Signatures of Super-Earths: How to Distinguish Between Hydrogen-Rich and Hydrogen-Poor Atmospheres
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST
• Ranges of Atmospheric Mass and Composition of Super Earth Exoplanets
• Thermodynamics of Element Volatility and its Application to Planetary Processes