{"id":193426,"date":"2025-12-20T13:14:16","date_gmt":"2025-12-20T13:14:16","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/193426\/"},"modified":"2025-12-20T13:14:16","modified_gmt":"2025-12-20T13:14:16","slug":"double-cosmic-explosion-gives-birth-to-unprecedented-superkilonova","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/193426\/","title":{"rendered":"Double Cosmic Explosion Gives Birth to Unprecedented \u2018Superkilonova\u2019"},"content":{"rendered":"

When massive stars die, they go out in fiery explosions called supernovas. On rarer occasions, two nearly dead stars collide to create dimmer yet similarly intense kilonovas. On even rarer occasions, the supernovas and kilonovas overlap in a superkilonova\u2014at least, that\u2019s the best explanation at the moment.<\/p>\n

In a recent paper for The Astrophysical Journal Letters<\/a>, astronomers led by the California Institute of Technology describe an odd stellar explosion highly likely to be somehow both a supernova and a kilonova. To be exact, a supernova birthed two neutron stars\u2014dense, practically dead stellar cores\u2014which then merged to create a kilonova.<\/p>\n

If confirmed, the signal, dubbed AT2025ulz, would be the second kilonova ever to be detected and the first of its kind to have emerged in such a complex manner.<\/p>\n

Explosions to ripples <\/p>\n

When stars explode at the end of their lifespans, the explosions help seed the universe with heavier elements like carbon and iron. Kilonovas, on the other hand, release even heavier elements, such as gold and uranium, which then become the basic building blocks of more stars and rockier planets.<\/p>\n

Such cataclysmic events create ripples in spacetime\u2014gravitational waves<\/a>\u2014that detectors like LIGO pick up on Earth. Humanity had documented kilonovas only once, back in 2017<\/a>, also with LIGO. So astronomers were ecstatic when, in August this year, the same facility sent an alert to the community, advising them of a signal that appeared to resemble that historical detection.<\/p>\n

Almost immediately, another survey camera confirmed rapidly fading red lights\u2014a sign of heavy element production from kilonovas\u2014originating from the same location. A few days later, the source flared again, but this time in blue, more like a supernova.<\/p>\n

\"KilonovaAn artist\u2019s impression of the kilonova signal AT2025ulz. Credit: Caltech\/K. Miller and R. Hurt (IPAC) Stellar detectives <\/p>\n

\u201cAt first, for about three days, the eruption looked just like the first kilonova in 2017,\u201d Mansi Kasliwal, study lead author and an astrophysicist at Caltech, said in a release<\/a>. \u201cEverybody was intensely trying to observe and analyze it, but then it started to look more like a supernova, and some astronomers lost interest. Not us.\u201d<\/p>\n

For Kasliwal, there were too many unanswered questions about AT2025ulz to conclude it was a supernova. For one, it didn\u2019t resemble an average supernova\u2014or, for that matter, the kilonova observed in 2017. What\u2019s more, the gravitational wave data pointed to the merger of two objects, at least one of which was unusually light.<\/p>\n

\u201cNo neutron star had ever been observed before with a mass less than that of the Sun, and it was believed to be theoretically impossible,\u201d said Brian Metzger, study co-author and a theoretical physicist at Columbia University, in a statement<\/a>. But that was what LIGO found: a sub-solar neutron star engaged in an explosive merger.<\/p>\n

An unfinished investigation <\/p>\n

Theoretically, the best explanation for the lightweight neutron stars would be the product of a rapidly spinning massive star splitting into two during a supernova, Metzger said. But the general chaos throughout the process would additionally force the baby neutron stars into a deadly spiral that ends with a kilonova, he added.<\/p>\n

\"NeutronstarsAn artist\u2019s impression of two small neutron stars. Credit: Caltech\/K. Miller and R. Hurt (IPAC) <\/p>\n

All that said, this explanation, while \u201ctantalizing,\u201d must be tested further, the researchers admitted. After all, AT2025ulz\u2014if it is a kilonova\u2014represents just the second kilonova to be detected.<\/p>\n

\u201cFuture kilonovae events may not look like GW170817 and may be mistaken for supernovae,\u201d Kasliwal said. \u201cWe do not know with certainty that we found a superkilonova, but the event nevertheless is eye-opening.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"When massive stars die, they go out in fiery explosions called supernovas. On rarer occasions, two nearly dead…\n","protected":false},"author":2,"featured_media":193427,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[37148,40171,111,139,69,393,147,89771],"class_list":{"0":"post-193426","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-gravitational-wave","9":"tag-ligo","10":"tag-new-zealand","11":"tag-newzealand","12":"tag-nz","13":"tag-physics","14":"tag-science","15":"tag-supernovas"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/193426","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=193426"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/193426\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/193427"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=193426"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=193426"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=193426"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}