{"id":2735,"date":"2026-05-28T19:23:08","date_gmt":"2026-05-28T17:23:08","guid":{"rendered":"http:\/\/localhost\/messier\/m21"},"modified":"2026-06-04T12:06:39","modified_gmt":"2026-06-04T10:06:39","slug":"m21-2","status":"publish","type":"messier_object","link":"https:\/\/voyage-astrophoto.fr\/index.php\/messier\/m21-2\/","title":{"rendered":"M21 &#8211; Amas Ouvert M21"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">M21 fut d\u00e9couvert par Charles Messier le 3 juin 1764. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Cet amas ouvert est situ\u00e9 \u00e0 environ 4 250 ann\u00e9es-lumi\u00e8re de la Terre, relativement proche en comparaison d&rsquo;autres objets du catalogue. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Il contient environ 57 \u00e9toiles regroup\u00e9es sur un diam\u00e8tre d&rsquo;environ 19 ann\u00e9es-lumi\u00e8re. Avec un \u00e2ge estim\u00e9 \u00e0 environ 4,6 millions d&rsquo;ann\u00e9es, M21 est un amas ouvert relativement jeune, contenant encore des \u00e9toiles de type OB chaudes et lumineuses. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L&rsquo;amas est suffisamment lumineux pour \u00eatre observable avec des jumelles et constitue un bon objet d&rsquo;introduction pour les d\u00e9butants en astronomie. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Il est situ\u00e9 \u00e0 proximit\u00e9 de M20, la N\u00e9buleuse Trifide, permettant d&rsquo;observer les deux objets dans le m\u00eame champ de vision. <\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em>Sources: SEDS Messier Database, Wikipedia, NASA.<\/em><\/p>\n","protected":false},"featured_media":0,"template":"","meta":[],"class_list":["post-2735","messier_object","type-messier_object","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/voyage-astrophoto.fr\/index.php\/wp-json\/wp\/v2\/messier_object\/2735","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/voyage-astrophoto.fr\/index.php\/wp-json\/wp\/v2\/messier_object"}],"about":[{"href":"https:\/\/voyage-astrophoto.fr\/index.php\/wp-json\/wp\/v2\/types\/messier_object"}],"wp:attachment":[{"href":"https:\/\/voyage-astrophoto.fr\/index.php\/wp-json\/wp\/v2\/media?parent=2735"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}