{"id":134,"date":"2026-07-22T15:42:21","date_gmt":"2026-07-22T20:42:21","guid":{"rendered":"http:\/\/aj-website-pi.local\/?p=134"},"modified":"2026-07-22T15:42:21","modified_gmt":"2026-07-22T20:42:21","slug":"westerlund-1","status":"publish","type":"post","link":"https:\/\/thestarguru.com\/index.php\/2026\/07\/22\/westerlund-1\/","title":{"rendered":"Westerlund 1"},"content":{"rendered":"\n

Westerlund 1 is a red supergiant cluster in the constellation Ara. As its name suggests, it was discovered by Bengt Westerlund in 1961. Westerlund also discovered the largest known star, WOH G64. Westerlund 1 is notable for containing four extreme red supergiant stars. Westerlund 1 also contains six yellow hypergiants, 24 Wolf Rayets, and a Luminous blue variable among many other star types. The cluster is located 3.78 Kiloparsecs from Earth.<\/p>\n\n\n\n

Red Supergiant Stars within the cluster<\/h2>\n\n\n\n

Westerlund 1 contains four red supergiant stars, which all are contenders for the title of largest known star. Westerlund 1-237 is currently the largest of the four. Below is the astronomical data for the four:<\/p>\n\n\n\n

Westerlund 1-237<\/strong><\/p>\n\n\n\n

Radius (in Solar Radii): 1,245 R<\/em>\u2609<\/sub><\/p>\n\n\n\n

Diameter (in Kilometers): 1,733,040,000 km<\/p>\n\n\n\n

Spectral type: M3Ia (Red)<\/p>\n\n\n\n

Westerlund 1-26<\/strong><\/p>\n\n\n\n

Radius (in Solar Radii): 1,145 R<\/em>\u2609<\/sub><\/p>\n\n\n\n

Diameter (in Kilometers): 1,593,840,000 km<\/p>\n\n\n\n

Spectral type: M0.5 (Red)<\/p>\n\n\n\n

Westerlund 1-20<\/strong><\/p>\n\n\n\n

Radius (in Solar Radii): 858 R<\/em>\u2609<\/sub><\/p>\n\n\n\n

Diameter (in Kilometers): 1,194,336,000 km<\/p>\n\n\n\n

Spectral type: M6I (Red)<\/p>\n\n\n\n

Westerlund 1-75<\/strong><\/p>\n\n\n\n

Radius (in Solar Radii): 722 R<\/em>\u2609<\/sub><\/p>\n\n\n\n

Diameter (in Kilometers): 1,005,024,000 km<\/p>\n\n\n\n

Spectral type: M4Ia (Red)<\/p>\n\n\n\n

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Size comparison of the red supergiants located within the Westerlund 1 cluster<\/mark><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

Westerlund 1 is a red supergiant cluster in the constellation Ara. As its name suggests, it was discovered by Bengt Westerlund in 1961. Westerlund also discovered the largest known star, WOH G64. Westerlund 1 is notable for containing four extreme red supergiant stars. Westerlund 1 also contains six yellow hypergiants, 24 Wolf Rayets, and a Luminous blue variable among many… Continue reading Westerlund 1<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":136,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[33,32],"tags":[],"class_list":["post-134","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-dsos-in-the-constellation-ara","category-star-clusters","entry"],"_links":{"self":[{"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/posts\/134","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/comments?post=134"}],"version-history":[{"count":1,"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/posts\/134\/revisions"}],"predecessor-version":[{"id":137,"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/posts\/134\/revisions\/137"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/media\/136"}],"wp:attachment":[{"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/media?parent=134"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/categories?post=134"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thestarguru.com\/index.php\/wp-json\/wp\/v2\/tags?post=134"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}