{"paper":{"title":"Magnesium in the atmosphere of the planet HD209458b: Observations of the thermosphere-exosphere transition region","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.EP","authors_text":"A. Lecavelier des Etangs, A. Vidal-Madjar, C. M. Huitson, D. Ehrenreich, D. K. Sing, G. Ballester, G. H\\'ebrard, J. C. McConnell, J.-M. D\\'esert, R. Ferlet, V. Bourrier","submitted_at":"2013-10-30T11:24:16Z","abstract_excerpt":"We report new near ultraviolet HST/STIS observations of atmospheric absorptions during the planetary transit of HD209458b. We detect absorption in atomic magnesium (MgI), while no signal has been detected in the lines of singly ionized magnesium (MgII). We measure the MgI atmospheric absorption to be 6.2+/-2.9% in the velocity range from -62 to -19 km/s. The detection of atomic magnesium in the planetary upper atmosphere at a distance of several planetary radii gives a first view into the transition region between the thermosphere and the exobase, where atmospheric escape takes place. We estim"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1310.8104","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":""},"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"}