{"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-thermal-emission-spectrum-of-the-nearby","title":"The Thermal Emission Spectrum of the Nearby Rocky Exoplanet LTT 1445A b from JWST MIRI/LRS","arxiv_id":"2410.10987","date":"2024-10-14","proceeding":null,"authors":["Patcharapol Wachiraphan","Zachory K. Berta-Thompson","Hannah Diamond-Lowe","Jennifer G. Winters","Catriona Murray","Michael Zhang","Qiao Xue","Caroline V. Morley","Marialis Rosario-Franco","Girish M. Duvvuri"],"abstract":"The nearby transiting rocky exoplanet LTT 1445A b presents an ideal target for studying atmospheric retention in terrestrial planets orbiting M dwarfs. It is cooler than many rocky exoplanets yet tested for atmospheres, receiving a bolometric instellation similar to Mercury's. Previous transmission spectroscopy ruled out a light H/He-dominated atmosphere but could not distinguish between a bare-rock, a high-MMW, or a cloudy atmosphere. We present new secondary eclipse observations using JWST's MIRI/LRS, covering the 5-12 $\\mu$m range. From these observations, we detect a broadband secondary eclipse depth of 41 $\\pm$ 9 ppm and measure a mid-eclipse timing consistent with a circular orbit (at 1.7$\\sigma$). From its emission spectrum, the planet's dayside brightness temperature is constrained to 525 $\\pm$ 15 K, yielding a temperature ratio relative to the maximum average dayside temperature from instant thermal reradiation by a rocky surface $R$ = $T_{\\rm day,obs}/T_{\\rm max}$ = 0.952 $\\pm$ 0.057, consistent with emission from a dark rocky surface. From an energy balance perspective, such a warm dayside temperature disfavors thick atmospheres, excluding $\\sim$100 bar atmospheres with Bond albedo $>$ 0.08 at the 3$\\sigma$ level. Furthermore, forward modeling of atmospheric emission spectra disfavor simple 100\\% CO$_2$ atmospheres with surface pressures of 1, 10, and 100 bar at 4.2$\\sigma$, 6.6$\\sigma$, and 6.8$\\sigma$ confidence, respectively. These results suggest that LTT 1445A b lacks a very thick CO$_2$ atmosphere, possibly due to atmospheric erosion driven by stellar activity. However, the presence of a moderately thin atmosphere (similar to those on Mars, Titan, or Earth) remains uncertain.","url_abs":"https://arxiv.org/abs/2410.10987v1","url_pdf":"https://arxiv.org/pdf/2410.10987v1.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-thermal-emission-spectrum-of-the-nearby","repo_url":"https://github.com/zkbt/exoplanet-atlas","is_official":1,"mentioned_in_paper":0,"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}