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Main Authors: Jordan, Sean, Shorttle, Oliver, Rimmer, Paul B.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2501.17948
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author Jordan, Sean
Shorttle, Oliver
Rimmer, Paul B.
author_facet Jordan, Sean
Shorttle, Oliver
Rimmer, Paul B.
contents The circumstellar liquid-water habitable zone guides our search for potentially inhabited exoplanets, but remains observationally untested. We show that the inner edge of the habitable zone can now be mapped among exoplanets using their lack of surface water, which, unlike the presence of water, can be unambiguously revealed by atmospheric sulfur species. Using coupled climate-chemistry modelling we find that the observability of sulfur-gases on exoplanets depends critically on the ultraviolet (UV) flux of their host star, a property with wide variation: most M-dwarfs have a low UV flux and thereby allow the detection of sulfur-gases as a tracer of dry planetary surfaces; however, the UV flux of Trappist-1 may be too high for sulfur to disambiguate uninhabitable from habitable surfaces on any of its planets. We generalise this result to show how a population-level search for sulfur-chemistry on M-dwarf planets can be used to empirically define the Habitable Zone in the near-future.
format Preprint
id arxiv_https___arxiv_org_abs_2501_17948
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Tracing the Inner Edge of the Habitable Zone with Sulfur Chemistry
Jordan, Sean
Shorttle, Oliver
Rimmer, Paul B.
Earth and Planetary Astrophysics
The circumstellar liquid-water habitable zone guides our search for potentially inhabited exoplanets, but remains observationally untested. We show that the inner edge of the habitable zone can now be mapped among exoplanets using their lack of surface water, which, unlike the presence of water, can be unambiguously revealed by atmospheric sulfur species. Using coupled climate-chemistry modelling we find that the observability of sulfur-gases on exoplanets depends critically on the ultraviolet (UV) flux of their host star, a property with wide variation: most M-dwarfs have a low UV flux and thereby allow the detection of sulfur-gases as a tracer of dry planetary surfaces; however, the UV flux of Trappist-1 may be too high for sulfur to disambiguate uninhabitable from habitable surfaces on any of its planets. We generalise this result to show how a population-level search for sulfur-chemistry on M-dwarf planets can be used to empirically define the Habitable Zone in the near-future.
title Tracing the Inner Edge of the Habitable Zone with Sulfur Chemistry
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2501.17948