{"id":65168,"date":"2025-01-31T12:00:00","date_gmt":"2025-01-31T12:00:00","guid":{"rendered":"https:\/\/www.africa-press.net\/senegal\/politique\/cette-super-terre-intrigue-les-scientifiques-en-raison-de-son-orbite-excentrique"},"modified":"2025-01-31T12:00:00","modified_gmt":"2025-01-31T12:00:00","slug":"cette-super-terre-intrigue-les-scientifiques-en-raison-de-son-orbite-excentrique","status":"publish","type":"post","link":"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/cette-super-terre-intrigue-les-scientifiques-en-raison-de-son-orbite-excentrique","title":{"rendered":"Cette Super-Terre Intrigue les Scientifiques en Raison de Son Orbite Excentrique"},"content":{"rendered":"<p><span style=\"color: #ff6600\"><strong>Africa-Press &#8211; Senegal. <\/strong><\/span>Vingt longues anne\u0301es auront e\u0301te\u0301 ne\u0301cessaires pour identifier HD 20794 d, une exoplane\u0300te situe\u0301e toute proche du Soleil, a\u0300 tout juste 19,7 anne\u0301es-lumie\u0300re. Et les astronomes de l\u2019Unige (Universite\u0301 de Gene\u0300ve, Suisse) ont du\u0302 avoir recours aux instruments les plus sophistique\u0301s pour arriver a\u0300 la de\u0301nicher.<\/p>\n<p><b>Une orbite elliptique entre glace et eau liquide<\/b><\/p>\n<p>HD 20794 d est une super-Terre, c\u2019est-a\u0300-dire une plane\u0300te tellurique plus massive que la Terre qui gravite (en compagnie de deux autres plane\u0300tes identifie\u0301es) autour de HD 20794, une e\u0301toile similaire au Soleil. Elle pre\u0301sente une orbite remarquable, fortement excentrique. Alors que la plupart des plane\u0300tes du syste\u0300me solaire suivent des trajectoires quasi circulaires, cette exoplane\u0300te s\u2019e\u0301loigne et se rapproche de son e\u0301toile, traversant pe\u0301riodiquement sa zone habitable. Il s\u2019agit d\u2019une re\u0301gion d\u2019un syste\u0300me plane\u0301taire, ou\u0300 l\u2019eau pourrait exister sous forme liquide et qui est situe\u0301e pour ce type d\u2019e\u0301toile entre 0,75 et 1,5 unite\u0301 astronomique.<\/p>\n<p>HD 20794 d met, quant a\u0300 elle, 647 jours pour boucler une re\u0301volution comple\u0300te, soit une quarantaine de jours de moins que la plane\u0300te Mars autour du Soleil. Mais son orbite elliptique l\u2019ame\u0300ne a\u0300 la limite inte\u0301rieure de la zone habitable lorsqu\u2019elle est la plus proche de son e\u0301toile (a\u0300 0.75 ua) et en dehors de la zone lorsqu\u2019elle est la plus e\u0301loigne\u0301e de son e\u0301toile (a\u0300 2 ua). Cette oscillation offre une occasion unique d\u2019affiner les mode\u0300les the\u0301oriques de l\u2019habitabilite\u0301 plane\u0301taire. \u00ab HD 20794 est une e\u0301toile exceptionnelle pour ce type d\u2019e\u0301tude, car sa proximite\u0301 et sa luminosite\u0301 permettent une caracte\u0301risation plus fine de ses plane\u0300tes \u00bb, explique dans un communique\u0301 Xavier Dumusque, coauteur de l\u2019e\u0301tude publie\u0301e dans la revue Astronomy and Astrophysics.<\/p>\n<p><b>Une de\u0301couverte apre\u0300s 20 ans d\u2019observations<\/b><\/p>\n<p>Repe\u0301rer une plane\u0300te aussi particulie\u0300re n\u2019a pas e\u0301te\u0301 une ta\u0302che aise\u0301e. Pendant deux de\u0301cennies, les chercheurs ont accumule\u0301 des donne\u0301es gra\u0302ce a\u0300 des instruments de pointe tels que les spectrographes HARPS et ESPRESSO, des instruments capables de de\u0301tecter les variations de vitesse radiale induites par la pre\u0301sence de plane\u0300tes, infimes par nature. Cependant, les signaux plane\u0301taires e\u0301taient masque\u0301s par des artefacts, ce qui rendait leur identification difficile. La solution est venue de YARARA, un algorithme de\u0301veloppe\u0301 a\u0300 l\u2019universite\u0301 de Gene\u0300ve, qui a permis d\u2019e\u0301liminer ces interfe\u0301rences et de re\u0301ve\u0301ler la pre\u0301sence de HD 20794 d.<\/p>\n<p>Cette de\u0301couverte s\u2019inscrit dans une de\u0301marche plus large visant a\u0300 identifier les conditions ne\u0301cessaires a\u0300 l\u2019apparition de la vie ailleurs dans l\u2019Univers. La proximite\u0301 relative, avec HD 20794 d ainsi que la luminosite\u0301 de son e\u0301toile, font de ce syste\u0300me une cible de choix pour les instruments de nouvelle ge\u0301ne\u0301ration comme le spectrographe ANDES de l\u2019Extre\u0302mement Grand Te\u0301lescope (ELT) de l\u2019ESO. Avec ceux-ci, les astronomes espe\u0300rent biento\u0302t analyser les atmosphe\u0300res de ces plane\u0300tes. \u00ab Ce syste\u0300me est un ve\u0301ritable laboratoire pour comprendre l\u2019habitabilite\u0301 et les processus menant a\u0300 l\u2019apparition de la vie \u00bb, conclut Michael Cretignier, coauteur de l\u2019e\u0301tude.<\/p>\n<p><strong>Pour plus d&rsquo;informations et d&rsquo;analyses sur la <span style=\"color: #ff6600\">Senegal<\/span>, suivez <span style=\"color: #ff6600\">Africa-Press<span style=\"color: #ff6600\"><\/span><\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Africa-Press &#8211; Senegal. Vingt longues anne\u0301es auront e\u0301te\u0301 ne\u0301cessaires pour identifier HD 20794 d, une exoplane\u0300te situe\u0301e toute proche du Soleil, a\u0300 tout juste 19,7 anne\u0301es-lumie\u0300re. Et les astronomes de l\u2019Unige (Universite\u0301 de Gene\u0300ve, Suisse) ont du\u0302 avoir recours aux instruments les plus sophistique\u0301s pour arriver a\u0300 la de\u0301nicher. Une orbite elliptique entre glace et [&hellip;]<\/p>\n","protected":false},"author":82,"featured_media":65167,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,10],"tags":[44],"class_list":["post-65168","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-divers","category-toutes-les-actualites","tag-senegal-2"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v26.1 (Yoast SEO v27.0) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>Cette Super-Terre Intrigue les Scientifiques en Raison de Son Orbite Excentrique - Senegal<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.africa-press.net\/senegal\/politique\/cette-super-terre-intrigue-les-scientifiques-en-raison-de-son-orbite-excentrique\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Cette Super-Terre Intrigue les Scientifiques en Raison de Son Orbite Excentrique\" \/>\n<meta property=\"og:description\" content=\"Africa-Press &#8211; Senegal. Vingt longues anne\u0301es auront e\u0301te\u0301 ne\u0301cessaires pour identifier HD 20794 d, une exoplane\u0300te situe\u0301e toute proche du Soleil, a\u0300 tout juste 19,7 anne\u0301es-lumie\u0300re. Et les astronomes de l\u2019Unige (Universite\u0301 de Gene\u0300ve, Suisse) ont du\u0302 avoir recours aux instruments les plus sophistique\u0301s pour arriver a\u0300 la de\u0301nicher. 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