Tracing the inner edge of the habitable zone with sulfur chemistry.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39879310.
- Also identified by DOI 10.1126/sciadv.adp8105 and PMC identifier 11777254.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
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 modeling, 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 generalize 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.