Destroyed by a black hole: Explanation for mysterious blue stellar explosion
For years, telescopes have been finding extremely energetic blue stellar explosions that could not be explained until now. Now there is supposedly an answer.
Image of AT 2024wpp, the brightest LFBOT to date
(Image: International Gemini Observatory/CTIO/NOIRLab/DOE/NSF/AURA/NASA/ESA/Hubble/Swift/CXC/ALMA (ESO/NAOJ/NRAO)/Bildbearbeitung: J. Miller & M. Rodriguez (International Gemini Observatory/NSF NOIRLab), T.A. Rector (University of Alaska Anchorage/NSF NOIRLab), D. de Martin & M. Zamani (NSF NOIRLab))
After astronomers have discovered more and more extremely bright, blue explosions in recent years that they could not explain until now, an international research group now believes to have found an answer. The so-called fast blue optical transients (“FBOT” or “LFBOT”) are said to arise when a massive black hole completely destroys a star within days. Previous explanations for the mysterious phenomena are therefore incorrect. This is claimed by the group based on a comprehensive analysis of the brightest of these explosions observed last year.
Cannot be explained as a supernova
The first of these explosions was discovered 11 years ago, explains NOIRLab from the USA, which has now contributed to the financing of the analysis. Since then, more than a dozen others have been found, and there is even a naming scheme. One of the most important LFBOTs was observed in 2018; it is designated AT 2018cow (also called “The Cow” due to the last three letters); others are named ZTF18abvkwla (“The Koala”), AT 2022tsd (“The Tasmanian Devil”), and AT 2023fhn (“The Finch”). AT 2024wpp (possibly soon “The Wasp” in line with the naming convention), the brightest of these flashes of light, has now been analyzed.
(Image:Â NOIRLab/NSF/AURA/R. Margutti/P. Marenfeld)
The research group has found that AT 2024wpp could not be attributed to a supernova. 100 times more energy was emitted than is possible in such an explosion at the end of a star's life. This would have required 10 percent of the mass of the progenitor star to be converted into energy within weeks. No known type of stellar explosion is capable of this. Explanations based on this are therefore incorrect, and alternative models were necessary. Observations with the Gemini Observatory in Chile, among others, helped, in which an excess of near-infrared light was found in the radiation.
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According to the reconstruction, the star system, 1.1 billion light-years away, where the explosion occurred, consisted of a black hole and a star. The former has a mass of about 100 suns and had been drawing material from the star with 10 solar masses for a long time. This surrounded the black hole but was too far away from it to fall in. When the star finally came too close, it was torn apart. The released material was dragged into this cloud. During this collision, the enormous amount of energy was released as X-ray and ultraviolet radiation, as well as blue light, among other things. Material was ejected into space at 40 percent of the speed of light. This is described in two scientific articles [Link to https://arxiv.org/pdf/2509.00951].
(mho)
