Sulfur-driven haze formation in warm CO2-rich exoplanet atmospheres

Chao He, Sarah M. Hörst, Nikole K. Lewis, Xinting Yu, Julianne I. Moses, Patricia McGuiggan, Mark S. Marley, Eliza M.R. Kempton, Sarah E. Moran, Caroline V. Morley, Véronique Vuitton

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Sulfur gases substantially affect the photochemistry of planetary atmospheres in our Solar System, and are expected to be important components in exoplanet atmospheres. However, sulfur photochemistry in the context of exoplanets is poorly understood due to a lack of chemical kinetics information for sulfur species under relevant conditions. Here, we study the photochemical role of hydrogen sulfide (H2S) in warm CO2-rich exoplanet atmospheres (800 K) by carrying out laboratory simulations. We find that H2S plays a prominent role in photochemistry, even when present in the atmosphere at relatively low concentrations (1.6%). It participates in both gas and solid phase chemistry, leading to the formation of other sulfur gas products (CH3SH/SO, C2H4S/OCS, SO2/S2 and CS2) and to an increase in solid haze particle production and compositional complexity. Our study shows that we may expect thicker haze with small particle sizes (20–140 nm) for warm CO2-rich exoplanet atmospheres that possess H2S.

Original languageEnglish (US)
Pages (from-to)986-993
Number of pages8
JournalNature Astronomy
Issue number10
StatePublished - Oct 1 2020
Externally publishedYes

ASJC Scopus subject areas

  • Astronomy and Astrophysics


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