A star appears to be locked in a lethal dance with a supermassive black hole. According to a team of astronomers, this unlucky star gets almost torn apart each time its orbit swings past the black hole on a tight loop. If they are right, we might see it happen again two years from now.
If a star gets close enough to a supermassive black hole at the centre of a galaxy, it can be tidally disrupted, which means the black hole鈥檚 gravitational field stretches the star and siphons off material, producing a burst of radiation that can be observed from Earth. Stars are often destroyed in the process, but they can also survive in what are called partial tidal disruption events.
at the University of Science and Technology of China in Hefei and his colleagues say they have spotted a star that has undergone two partial disruptions, around 710 days apart.
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Lin and his team first spotted a flare in 2022, in a galaxy around 400 million light years from Earth. In January 2024, they observed a second flare from the same galaxy.
After comparing the spectroscopic pattern of light from the two flares, they concluded that they appeared to have come from the same star. 鈥淲ith the spectroscopy, we see some special fingerprints in this event,鈥� says Lin. In a paper reporting their findings, they call it 鈥渢he unluckiest star鈥�.
Despite the similarities between the two observations, more evidence is required to say they come from the same star, says at the Open University in the UK. 鈥淐laiming something is periodic on the basis of two observations is stretching things.鈥�
For the star to orbit around the black hole every 710 days would also require a highly unusual orbit, he says. 鈥淚t鈥檚 an ellipse that鈥檚 squashed down so much it鈥檚 essentially a straight line, in and out again,鈥� says Norton. 鈥淭hat鈥檚 the only way this would work, is a periodic object to have that extreme eccentricity. To me, it seems a very unlikely situation.鈥�
Lin and his team hope to observe the star being disrupted a third time in another two years, which would make the situation clearer 鈥� but it is also possible that it was destroyed during the second flare.
鈥淚f it does give another flare exactly 710 days away from the second flare, then I might believe it. But at the moment, I must say I鈥檓 pretty sceptical,鈥� says Norton.
arXiv
