{"id":1983,"date":"2020-07-30T10:15:46","date_gmt":"2020-07-30T08:15:46","guid":{"rendered":"https:\/\/www-new.ias.u-psud.fr\/?p=1983"},"modified":"2026-08-07T12:01:53","modified_gmt":"2026-08-07T10:01:53","slug":"combien-de-temps-faut-il-pour-alterer-la-surface-dun-asteroide-glace","status":"publish","type":"post","link":"https:\/\/www.ias.u-psud.fr\/index.php\/2020\/07\/30\/combien-de-temps-faut-il-pour-alterer-la-surface-dun-asteroide-glace\/","title":{"rendered":"Combien de temps faut-il pour alt\u00e9rer la surface d\u2019un ast\u00e9ro\u00efde glac\u00e9 ?"},"content":{"rendered":"\t\t
\n\t\t\t\t
\n\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\"\"\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
\n\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t

Combien de temps faut-il pour alt\u00e9rer la surface d\u2019un ast\u00e9ro\u00efde glac\u00e9 ?<\/h1>\t\t\t\t<\/div>\n\t\t
\n \t\t
\n\t\t\t\t\t\t\t\t\t

Les surfaces des petits corps glac\u00e9s du syst\u00e8me solaire externe sont alt\u00e9r\u00e9es par l\u2019irradiation des ions \u00e9nerg\u00e9tiques solaires et cosmiques. Gr\u00e2ce \u00e0 une \u00e9tude exp\u00e9rimentale, des scientifiques de l\u2019\u00e9quipe \u00ab Astrochimie et Origines \u00bb de l\u2019IAS et du Florida Space Institute (USA) ont pu estimer ces effets pour certains de ces objets riches en m\u00e9thanol.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

\n\t\t\t\t\t
\n\t\t
\n \t\t
\n\t\t\t\t\t\t\t\t\t

Arrokoth, un petit corps glac\u00e9 de la ceinture de Kuiper, a \u00e9t\u00e9 d\u00e9couvert en 2014 gr\u00e2ce au t\u00e9lescope spatial Hubble. Il a \u00e9t\u00e9 choisi par l’\u00e9quipe New Horizons (NASA) comme cible de sa mission prolong\u00e9e dans le syst\u00e8me solaire externe, apr\u00e8s le survol de Pluton. Arrokoth est ainsi devenu l’objet le plus lointain jamais \u00e9tudi\u00e9 par une sonde spatiale. Depuis une altitude de 3500 km, les instruments \u00e0 bord de la sonde ont acquis des images et des spectres qui ont notamment mis en \u00e9vidence la pr\u00e9sence de glace de m\u00e9thanol. Ce compos\u00e9 a pr\u00e9c\u00e9demment \u00e9t\u00e9 d\u00e9tect\u00e9 sur d’autres objets du syst\u00e8me solaire externe, tels que le centaure 5145 Pholus et l’objet transneptunien (55638) 2002 VE95.<\/p>

Ces objets ont une autre caract\u00e9ristique commune : leur surface est rouge ! Ce \u00ab rougissement \u00bb de surface peut s’expliquer par la pr\u00e9sence de mati\u00e8re organique semi-r\u00e9fractaire m\u00e9lang\u00e9e aux glaces. Cette mati\u00e8re organique est alors soit h\u00e9rit\u00e9e telle quelle du nuage pr\u00e9-solaire ou du disque protoplan\u00e9taire, soit produite \u00e0 la surface de l\u2019objet \u00e0 la suite de sa longue exposition aux rayons cosmiques et\/ou aux particules \u00e9nerg\u00e9tiques solaires (SEP, pour Solar Energetic Particles).<\/p>

Pour y voir plus clair, l\u2019\u00e9quipe de l\u2019IAS s\u2019est appuy\u00e9e sur l’installation INGMAR-T (IAS\/CSNSM) coupl\u00e9e \u00e0 l\u2019acc\u00e9l\u00e9rateur d’ions SIDONIE (CSNSM) pour reproduire exp\u00e9rimentalement les conditions d’irradiation de la surface d’Arrokoth et d’autres objets riches en glace de m\u00e9thanol (Fig. 1). L\u2019analyse des spectres infrarouges exp\u00e9rimentaux post-irradiations et leur comparaison aux observations astronomiques et spatiales ont permis d\u2019estimer le temps d\u2019exposition \u00e0 l\u2019irradiation ionique de ces surfaces riches en m\u00e9thanol, selon l\u2019orbite o\u00f9 elles se situent.<\/p>

Tout d\u2019abord, l\u2019examen des spectres infrarouges indique que la surface de Pholus manifeste des signes clairs d\u2019exposition aux particules \u00e9nerg\u00e9tiques (Fig. 2), contrairement \u00e0 la surface d\u2019Arrokoth. L’\u00e9tude r\u00e9v\u00e8le ensuite, que parmi les diff\u00e9rentes populations de particules \u00e9nerg\u00e9tiques pr\u00e9sentes dans l’espace, les SEP sont les principales responsables de l’alt\u00e9ration de la surface de ces corps glac\u00e9s et, en cons\u00e9quence, de leur \u00ab rougeoiement \u00bb. Ces particules sont \u00e9mises par les r\u00e9gions actives solaires et par les \u00e9ruptions solaires (appel\u00e9es \u00ab flares \u00bb). \u00c9tant donn\u00e9 que l\u2019effet des SEP diminue avec la distance h\u00e9liocentrique, Arrokoth, qui est \u00e0 une distance plus \u00e9loign\u00e9e du Soleil que Pholus, est moins affect\u00e9 par les SEP que ce dernier. Cela signifie que pour observer des modifications de surface similaires, environ 6 millions d\u2019ann\u00e9es sont n\u00e9cessaires sur Pholus et environ 30 millions d\u2019ann\u00e9es sur Arrokoth.<\/p>

Les futures observations astronomiques du James Webb Space Telescope permettront d\u2019obtenir plus de d\u00e9tails sur ces objets. Les r\u00e9sultats obtenus \u00e0 l\u2019IAS seront alors utiles pour l\u2019interpr\u00e9tation des nouvelles observations et pour d\u00e9terminer la composition chimique et l\u2019\u00e9volution des objets du syst\u00e8me solaire externe.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

\n
\n \t\t\t\"\"\/\t\t\n<\/div>\n
\n \t\t\t\"\"\/\t\t\n<\/div>\n
\n \t\t\t

Fig. 1 : \u00e0 gauche, m\u00e9thanol \u00e0 la surface du KBO 486958 Arrokoth, adapt\u00e9 de NASA\/Johns Hopkins University Applied Physics Laboratory\/Southwest Research Institute\/Roman Tkachenko, Public domain ; \u00e0 droite : une repr\u00e9sentation sch\u00e9matique de l'exp\u00e9rience men\u00e9e \u00e0 l'IAS pour simuler l'irradiation de la surface d\u2019Arrokoth.<\/a><\/p>\n\t\t\n<\/div>\n

\n \t\t\t

Fig. 2: \u00e0 gauche, le spectre proche infrarouge de Pholus compar\u00e9 au spectre de laboratoire du m\u00e9thanol expos\u00e9 aux ions \u00e9nerg\u00e9tiques. La dose d\u00e9pend du temps d\u2019exposition aux ions \u00e9nerg\u00e9tiques ; \u00e0 droite, le rapport entre les aires des bandes infrarouges du m\u00e9thanol est le param\u00e8tre spectroscopique choisi pour \u00e9tudier l\u2019alt\u00e9ration des surfaces d\u2019Arrokoth et de Pholus.<\/a> <\/p>\n\t\t\n<\/div>\n\n<\/div>\n

\n\t\t
\n\t\t\t\t
\n\t\t\t\t\t

Contacts<\/h2>\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t

R\u00e9f\u00e9rents (scientifiques et techniques) <\/h2>\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\t

Riccardo Giovanni Urso<\/a><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

\n\t\t\t\t
\n\t\t\t\t\t

R\u00e9f\u00e9rences<\/h2>\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t\t\t\t\t

Urso, R. G., Baklouti, D., Djouadi, Z., Pinilla-Alonso, N. & Brunetto, R., 2020. Near-infrared Methanol Bands Probe Energetic Processing of Icy Outer Solar System Objects. ApJ Letters, 894, 1, L3, https:\/\/doi.org\/10.3847\/2041-8213\/ab8ad9<\/a><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"

Les surfaces des petits corps glac\u00e9s du syst\u00e8me solaire externe sont alt\u00e9r\u00e9es par l\u2019irradiation des ions \u00e9nerg\u00e9tiques solaires et cosmiques.<\/p>\n","protected":false},"author":3,"featured_media":1996,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"elementor_header_footer","format":"standard","meta":{"inline_featured_image":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[5,24],"tags":[],"class_list":["post-1983","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news-scientifiques-home","category-caps-scientifiques"],"_links":{"self":[{"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/posts\/1983","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/comments?post=1983"}],"version-history":[{"count":6,"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/posts\/1983\/revisions"}],"predecessor-version":[{"id":1998,"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/posts\/1983\/revisions\/1998"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/media\/1996"}],"wp:attachment":[{"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/media?parent=1983"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/categories?post=1983"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ias.u-psud.fr\/index.php\/wp-json\/wp\/v2\/tags?post=1983"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}