2023-11-15 18:41:51
Artist’s rendering of AT2022tsd, an explosion in a distant galaxy. – ROBERT L. HURT/CALTECH/IPAC
MADRID, 15 Nov. (EUROPA PRESS) –
Following the explosive death of a distant star, an active stellar corpse was the likely source of repeated energetic flares observed for months, an unprecedented phenomenon.
This is reported by a team led by Cornell University in new research published in the magazine ‘Nature’.
The bright, brief flashes — just a few minutes long and as powerful as the original explosion 100 days later — appeared after a rare type of stellar cataclysm that researchers had set out to find, known as luminous fast blue optical transient (LFBOT, for its acronym in English).
Since their discovery in 2018, astronomers have speculated about what could drive such extreme explosions, which are much brighter than the violent extremes massive stars typically experience, but fade in days rather than weeks. The research team believes that the previously unknown flare activity, which was studied by 15 telescopes around the world, confirms that the engine must be a stellar corpse: a black hole or a neutron star.
“We do not believe there is anything else that could produce this type of flare,” Anna YQ Ho, associate professor of Astronomy in the College of Arts and Sciences, said in a statement. “This settles years of debate about what drives this type of explosion. , and reveals an unusually direct method of studying the activity of stellar corpses.”
Ho is the first author of the work, published with more than 70 co-authors which helped characterize the LFBOT officially labeled AT2022tsd and nicknamed “the Tasmanian devil”, and the resulting pulses of light seen about a billion light years from Earth. She wrote the computer program that detected the phenomenon in September 2022, while examining half a million changes or transients detected daily in a cosmic survey conducted by the California-based Zwicky Transient Facility.
In December 2022, while closely monitoring the explosion’s fading, Ho and his collaborators Daniel Perley of Liverpool John Moores University in England and Ping Chen of the Weizmann Institute of Science in Israel met to review the new observations made and analyzed by Ping: a set of five images each lasting several minutes. The first showed nothing, as expected, but the second caught light, followed by an intensely bright spike in the center frame that quickly disappeared.
“No one knew what to say,” he recalls. it’s a statement–. We have never seen anything like it, something as fast and as bright as the original explosion months later, in any supernova or FBOT. “We had never seen it, period, in astronomy.”
To further investigate the abrupt glow, researchers turned to collaborators who contributed observations from more than a dozen telescopes, including one equipped with a high-speed camera. The team examined previous data and ruled out other possible light sources. Their analysis ultimately confirmed at least 14 irregular light pulses over a period of 120 days, probably only a fraction of the total number, according to Ho.
“Surprisingly, instead of steadily fading away, as one would expect, the fountain briefly shone again, again and again,” he explains. “LFBOTs are already something of a strange and exotic event, so this was even more strange”.
Exactly what processes occurred remains to be studied, perhaps a black hole channeling jets of stellar material outward at near the speed of light. Ho is confident that this research will allow progress toward the long-sought goal of mapping how the properties of stars in life They can predict the way they will die and the type of corpse they will produce.
In the case of LFBOTs, rapid rotation or a strong magnetic field are likely key components of their launch mechanisms, Ho says. It is also possible that these are not conventional supernovae, but rather the merger of a star with a black hole. “We could be witnessing a completely different channel for cosmic cataclysms”he points out.
The unusual explosions promise to provide new knowledge about stellar life cycles, which are normally only observed in snapshots of different stages – star, explosion, remains. and not as part of a single system, says Ho. LFBOTs can offer the opportunity to observe a star as it transitions into its afterlife.
“Because the corpse is not just sitting there, it is active and doing things that we can detect,” says Ho. “We think these flares could come from one of these newly formed corpses, which gives us a way to study their properties when they have just formed.”
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