Abstract
ABSTRACT We present and validate a new network of atmospheric thermochemical and photochemical sulfur reactions. We use a 1D chemical kinetics model to investigate these reactions as part of a broader HCNO chemical network in a series of hot and warm Jupiters. We find that temperatures approaching $1400\, \mathrm{K}$ are favourable for the production of H2S and HS around $\mathrm{10^{-3}\, bar}$ at mixing ratios of around 10−5, an atmospheric level where detection by transit spectroscopy may be possible. At $\mathrm{10^{-3}\, bar}$ and at lower temperatures, down to $1000\, \mathrm{K}$, mixing ratios of S2 can be up to 10−5, at the expense of H2S and HS, which are depleted down to a mixing ratio of 10−7. We also investigate how the inclusion of sulfur can manifest in an atmosphere indirectly, by its effect on the abundance of non-sulfur-bearing species. We find that in a model of the atmosphere of HD 209458 b, the inclusion of sulfur can lower the abundance of NH3, CH4, and HCN by up to two orders of magnitude around $\mathrm{10^{-3}\, bar}$. In the atmosphere of the warm Jupiter 51 Eri b, we additionally find the inclusion of sulfur depletes the peak abundance of CO2 by a factor of 5, qualitatively consistent with prior models. We note that many of the reactions used in the network have poorly determined rate constants, especially at higher temperatures. To obtain an accurate idea of the impact of sulfur chemistry in hot and warm Jupiter atmospheres, experimental measurements of these reaction rates must take place.
Highlights
Sulfur chemistry is known to play an important role in the atmospheric chemistry of planets in our Solar system
We can investigate the importance of sulfur in the atmospheres of exoplanets in both the context of sulfur itself and the way it impacts carbon and oxygen chemistry. It was found in the work of Zahnle et al (2016) that sulfur photochemistry in the atmosphere of the warm Jupiter 51 Eri b was the source of a large number of radicals that went on to catalyze other chemistry
We investigate the simplest scenario for sulfur chemistry in hot Jupiters: an isothermal atmosphere model that is purely in local thermochemical equilibrium, without any form of diffusion or photochemistry
Summary
Sulfur chemistry is known to play an important role in the atmospheric chemistry of planets in our Solar system. We can investigate the importance of sulfur in the atmospheres of exoplanets in both the context of sulfur itself and the way it impacts carbon and oxygen chemistry It was found in the work of Zahnle et al (2016) that sulfur photochemistry in the atmosphere of the warm Jupiter 51 Eri b was the source of a large number of radicals that went on to catalyze other chemistry. This was a possible explanation for the difference in the CO2 abundance found for 51 Eri b between the sulfur-free models of Moses et al (2016) and the sulfurous models of Zahnle et al (2016).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
