Exoplanet Volatile Carbon Content as a Natural Pathway for Haze Formation
Abstract
We explore terrestrial planet formation with a focus on the supply of solid-state organics as the main source of volatile carbon. For the water-poor Earth, the water ice line, or ice sublimation front, within the planet-forming disk has long been a key focal point. We posit that the soot line, the location where solid-state organics are irreversibly destroyed, is also a key location within the disk. The soot line is closer to the host star than the water snow line and overlaps with the location of the majority of detected exoplanets. In this work, we explore the ultimate atmospheric composition of a body that receives a major portion of its materials from the zone between the soot line and water ice line. We model a silicate-rich world with 0.1% and 1% carbon by mass with variable water content. We show that as a result of geochemical equilibrium, the mantle of these planets would be rich in reduced carbon but have relatively low water (hydrogen) content. Outgassing would naturally yield the ingredients for haze production when exposed to stellar UV photons in the upper atmosphere. Obscuring atmospheric hazes appear common in the exoplanetary inventory based on the presence of often featureless transmission spectra. Such hazes may be powered by the high volatile content of the underlying silicate-dominated mantle. Although this type of planet has no solar system counterpart, it should be common in the galaxy with potential impact on habitability.
Additional Information
© 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. This research comes from an interdisciplinary collaboration initiated by the Integrated NSF Support Promoting Interdisciplinary Research and Education Program through grant AST1344133. Additional funding has been provided by National Aeronautics and Space Administration grants 80NSSC19K0959 (to M.M.H.), XRP NNX16AB48G (to G.A.B.), XRP 80NSSC20K0259 (to E.A.B. and F.J.C.), and 80GSFC21M0002 (to S.T.B); and National Science Foundation Grant AAG 2009095 (to E.M.-R.K. and supporting D.J.T.). S.T.B. also received support from the GSFC Sellers Exoplanet Environments Collaboration (SEEC), which is funded in part by the NASA Planetary Science Division's Internal Scientist Funding Model. This project is supported, in part, by funding from Two Sigma Investments, LP to EAB. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflects the views of Two Sigma Investments, LP. Facility: JWST. - Software: HELIOS (Malik et al. 2017, 2019), Exo-Transmit (Kempton et al. 2017; Teal et al. 2022).Attached Files
Published - Bergin_2023_ApJL_949_L17.pdf
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Additional details
- Eprint ID
- 121731
- Resolver ID
- CaltechAUTHORS:20230605-335040000.26
- AST-1344133
- NSF
- 80NSSC19K0959
- NASA
- NNX16AB48G
- NASA
- 80NSSC20K0259
- NASA
- AST-2009095
- NSF
- 80GSFC21M0002
- NASA
- Two Sigma Investments, LP
- Created
-
2023-06-08Created from EPrint's datestamp field
- Updated
-
2023-06-08Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences