{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/the-first-retrieval-of-a-substellar-subdwarf","title":"The first retrieval of a substellar subdwarf: A cloud-free SDSS J125637.13-022452.4","arxiv_id":"2109.11000","date":"2021-09-22","proceeding":null,"authors":["Eileen C. Gonzales","Ben Burningham","Jacqueline K. Faherty","Channon Visscher","Mark Marley","Roxana Lupu","Richard Freedman","Nikole K. Lewis"],"abstract":"We present the first retrieval analysis of a substellar subdwarf, SDSS J125637.13-022452.4 (SDSS J1256-0224), using the Brewster retrieval code base. We find SDSS J1256-0224 is best fit by a cloud-free model with an ion (neutral H, H-, and electron) abundance corresponding to ion [Fe/H]=-1.5. However, this model is indistinguishable from a cloud-free model with ion [Fe/H]=-2.0 and a cloud-free model with ion Fe/H]=-1.5 assuming a subsolar carbon-to-oxygen ratio. We are able to constrain abundances for water, FeH, and CrH, with an inability to constrain any carbon-bearing species likely due to the low-metallicity of SDSS J1256-0224. We also present an updated spectral energy distribution (SED) and semi-empirical fundamental parameters. Our retrieval- and SED-based fundamental parameters agree with the Baraffe low-metallicity evolutionary models. From examining our \"rejected\" models (those with $\\Delta$BIC>45), we find that we are able to retrieve gas abundances consistent with those of our best-fitting model. We find the cloud in these poorer fitting \"cloudy\" models is either pushed to the bottom of the atmosphere or made optically thin.","url_abs":"https://arxiv.org/abs/2109.11000v1","url_pdf":"https://arxiv.org/pdf/2109.11000v1.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"the-first-retrieval-of-a-substellar-subdwarf","repo_url":"https://github.com/hover2pi/SEDkit","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}