{"paper":{"title":"Magnesium Silicate Clouds in the Atmosphere of HD 209458b from a Rule-Based Tree-Structured Data Reduction","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["astro-ph.IM"],"primary_cat":"astro-ph.EP","authors_text":"Arika Egan, Charlotte Fairman, David Grant, David K. Sing, Diana Powell, Hannah R. Wakeford, Jeff A. Valenti, Katy L. Chubb, Kevin B. Stevenson, Lili Alderson, Mark Marley Elijah Mullens, Natasha E. Batalha, Nikole K. Lewis, Peter Gao, Ryan J. MacDonald, Sarah E. Moran, Tiffany Kataria","submitted_at":"2026-05-29T14:00:29Z","abstract_excerpt":"HD 209458b is the canonical hot Jupiter: the first to have its atmosphere measured and the first to hint at the role of aerosols in exoplanet atmospheres through the muting of Na absorption signatures in the optical. Here we present JWST MIRI/LRS transmission observations of HD 209458b from 5-12 microns, directly measuring the absorption signatures of its clouds for the first time. The observations indicate the presence of magnesium silicates, most likely Mg2SiO4 or a mixture of Mg2SiO4 and MgSiO3. We also present a new methodology to reduce observational data, whereby the analysis is formulat"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2606.00177","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2606.00177/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}