A JWST Transmission Spectrum of the Temperate Sub-Neptune TOI-732 c
Frances E. Rigby, Nikku Madhusudhan, Subhajit Sarkar, Lorenzo Pica-Ciamarra, M{\aa}ns Holmberg, Julianne I. Moses

TL;DR
This study presents JWST transmission spectra of the temperate sub-Neptune TOI-732 c, revealing methane and potential complex molecules, highlighting atmospheric composition complexities and the need for further observational and theoretical work.
Contribution
First detailed JWST transmission spectrum of TOI-732 c, identifying methane and possible complex molecules, advancing understanding of sub-Neptune atmospheres.
Findings
Detection of methane at ~1% volume mixing ratio.
Evidence for complex molecules including hydrocarbons and sulfur compounds.
Degeneracy among molecular signatures requiring further study.
Abstract
In recent years, JWST has facilitated detections of carbon-bearing molecules in the atmospheres of temperate sub-Neptunes orbiting M dwarfs, ushering in a new era in the characterization of this intriguing planetary regime. We report the transmission spectrum of the temperate sub-Neptune TOI-732 c, observed with JWST NIRISS, NIRSpec G395H and MIRI LRS between 0.9-12 m. The observations provide evidence for methane (CH) in a H-rich atmosphere, at a volume mixing ratio of 1\%, and non-detection of NH and HCN, along with nominal constraints on other prominent molecules HO, CO and CO, which are typically expected in H-rich atmospheres. We conduct a comprehensive survey of 250 chemical species and find moderate to strong evidence (up to , ) for additional absorption due to one or more complex molecules including higher-order…
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Taxonomy
TopicsAstro and Planetary Science · Astrophysics and Star Formation Studies · Astronomy and Astrophysical Research
