{"id":70538,"date":"2025-08-12T11:00:00","date_gmt":"2025-08-12T11:00:00","guid":{"rendered":"https:\/\/www.africa-press.net\/senegal\/?p=70538"},"modified":"2025-08-12T07:50:57","modified_gmt":"2025-08-12T07:50:57","slug":"petits-cailloux-dans-lunivers-et-planetes-formees","status":"publish","type":"post","link":"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees","title":{"rendered":"Petits Cailloux dans L\u2019Univers et Plan\u00e8tes Form\u00e9es"},"content":{"rendered":"

Africa-Press – Senegal. <\/strong><\/span>Ces petits cailloux qui mesurent de 1 a\u0300 quelques centime\u0300tres, se forment par agglome\u0301ration de grains de poussie\u0300re dans des anneaux de gaz et de matie\u0300re appele\u0301s disques protoplane\u0301taires, ces structures entourant les jeunes e\u0301toiles. Jusqu\u2019ici, les astronomes observaient aise\u0301ment les tout premiers stades de cette e\u0301volution (des poussie\u0300res microscopiques flottant dans les disques) ou bien les derniers re\u0301sultats, des plane\u0301te\u0301simaux constitue\u0301s. Mais l\u2019entre-deux leur e\u0301chappait en grande partie. C\u2019est de\u0301sormais en train de changer.<\/p>\n

Des graines de plane\u0300tes sur la bordure externe<\/b><\/p>\n

Lors de la re\u0301union annuelle de la Royal Astronomical Society a\u0300 Durham (Angleterre), qui s\u2019est de\u0301roule\u0301e du 7 au 11 juillet 2025, les chercheurs du projet PEBBLeS (Planet Earth Building-Blocks \u2013 a Legacy eMERLIN Survey) ont annonce\u0301 avoir identifie\u0301 de vastes zones contenant ces galets autour de DG Tau et HL Tau, deux jeunes e\u0301toiles en formation. Selon Katie Hesterly, de l\u2019observatoire SKA, \u00ab ces observations montrent que les disques de DG Tau et HL Tau contiennent de\u0301ja\u0300 de grandes quantite\u0301s de galets jusqu\u2019a\u0300 des distances e\u0301quivalentes a\u0300 l\u2019orbite de Neptune. C\u2019est potentiellement suffisant pour ba\u0302tir des syste\u0300mes plus vastes que le no\u0302tre \u00bb.<\/p>\n

Une e\u0301tape charnie\u0300re enfin re\u0301ve\u0301le\u0301e<\/b><\/p>\n

Depuis les anne\u0301es 1990, plus de 5000 exoplane\u0300tes ont e\u0301te\u0301 identifie\u0301es, et l\u2019on sait que de nombreuses e\u0301toiles jeunes sont entoure\u0301es de disques riches en gaz et en grains de poussie\u0300re. Mais selon Anita Richards, du Jodrell Bank Centre for Astrophysics, il est tre\u0300s difficile de suivre la croissance de ces grains. \u00ab Lorsque la matie\u0300re est disperse\u0301e, elle pre\u0301sente une grande surface et peut e\u0302tre de\u0301tecte\u0301e en infrarouge ou en submillime\u0301trique, comme avec ALMA. Mais a\u0300 mesure que les grains grossissent et se rassemblent, leur surface totale diminue et ils deviennent quasiment invisibles avec ces instruments \u00bb.<\/p>\n

C\u2019est pre\u0301cise\u0301ment la\u0300 qu\u2019e-MERLIN intervient, gra\u0302ce a\u0300 sa sensibilite\u0301 aux longueurs d\u2019onde centime\u0301triques. L\u2019image obtenue du disque de DG Tau re\u0301ve\u0300le ainsi la pre\u0301sence de galets a\u0300 grande distance de l\u2019e\u0301toile, la\u0300 ou\u0300 des plane\u0300tes gazeuses comme Neptune ou Uranus peuvent se former. HL Tau pre\u0301sente des caracte\u0301ristiques similaires, avec un anneau de matie\u0300re prometteur, a\u0300 l\u2019e\u0301chelle du syste\u0300me solaire.<\/p>\n

Ces re\u0301sultats laissent entrevoir les capacite\u0301s du futur SKA-Mid, un re\u0301seau de radiote\u0301lescopes en cours de construction en Afrique du Sud et en Australie. \u00ab e-MERLIN nous montre ce qu\u2019il est possible de faire \u00bb, re\u0301sume Katie Hesterly. \u00ab Lorsque les premie\u0300res observations scientifiques de SKA commenceront en 2031, nous pourrons e\u0301tudier des centaines de syste\u0300mes en formation, et comprendre enfin comment naissent les plane\u0300tes \u00bb.<\/p>\n

Pour plus d’informations et d’analyses sur la Senegal<\/span>, suivez Africa-Press<\/span><\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Africa-Press – Senegal. Ces petits cailloux qui mesurent de 1 a\u0300 quelques centime\u0300tres, se forment par agglome\u0301ration de grains de poussie\u0300re dans des anneaux de gaz et de matie\u0300re appele\u0301s disques protoplane\u0301taires, ces structures entourant les jeunes e\u0301toiles. Jusqu\u2019ici, les astronomes observaient aise\u0301ment les tout premiers stades de cette e\u0301volution (des poussie\u0300res microscopiques flottant dans […]<\/p>\n","protected":false},"author":82,"featured_media":70537,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,10],"tags":[44],"class_list":["post-70538","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-divers","category-toutes-les-actualites","tag-senegal-2"],"yoast_head":"\nPetits Cailloux dans L\u2019Univers et Plan\u00e8tes Form\u00e9es - Senegal<\/title>\n<meta name=\"description\" content=\"Ces petits cailloux qui mesurent de 1 a\u0300 quelques centime\u0300tres, se forment par agglome\u0301ration de grains de poussie\u0300re da ...\" \/>\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\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Petits Cailloux dans L\u2019Univers et Plan\u00e8tes Form\u00e9es\" \/>\n<meta property=\"og:description\" content=\"Ces petits cailloux qui mesurent de 1 a\u0300 quelques centime\u0300tres, se forment par agglome\u0301ration de grains de poussie\u0300re da ...\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees\" \/>\n<meta property=\"og:site_name\" content=\"Senegal\" \/>\n<meta property=\"article:published_time\" content=\"2025-08-12T11:00:00+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/static.africa-press.net\/senegal\/sites\/13\/2025\/08\/sm_1755013701.426772.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"720\" \/>\n\t<meta property=\"og:image:height\" content=\"490\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"cfeditorfr\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u00c9crit par\" \/>\n\t<meta name=\"twitter:data1\" content=\"cfeditorfr\" \/>\n\t<meta name=\"twitter:label2\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees\"},\"author\":{\"name\":\"cfeditorfr\",\"@id\":\"https:\/\/www.africa-press.net\/senegal\/#\/schema\/person\/2b1cf3cd81a31e3cd26889ca66d677f1\"},\"headline\":\"Petits Cailloux dans L\u2019Univers et Plan\u00e8tes Form\u00e9es\",\"datePublished\":\"2025-08-12T11:00:00+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees\"},\"wordCount\":511,\"commentCount\":0,\"image\":{\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees#primaryimage\"},\"thumbnailUrl\":\"https:\/\/static.africa-press.net\/senegal\/sites\/13\/2025\/08\/sm_1755013701.426772.jpg\",\"keywords\":[\"Senegal\"],\"articleSection\":[\"Divers\",\"Toutes les actualit\u00e9s\"],\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees\",\"url\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/petits-cailloux-dans-lunivers-et-planetes-formees\",\"name\":\"Petits Cailloux dans L\u2019Univers et Plan\u00e8tes Form\u00e9es - 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