Astronomers have observed a star like the sun being “repeatedly shredded and consumed” by a black hole about 500m light years away.
The dramatic event generated regular outbursts of light about every 25 days, which was detected by scientists at the University of Leicester.
Normally, black hole outbursts – known as tidal disruption events – appear when a black hole consumes a star, but repeated emissions mean they are only partially destroying stars again and again.
In instances where there are repeated eruptions, two types of outbursts occur: those that take place every few hours and those that happen every year or so, according to the researchers.
In this case the regularity of emissions fell between the two, the team said.
Observations showed that instead of decaying as expected, the star – Swift J0230 – would shine brightly for seven to 10 days and then abruptly switch off, repeating this process roughly every 25 days. The researchers said their work, published in the journal Nature Astronomy, provided a missing link in the understanding of how black holes disrupt orbiting stars.
Dr Robert Eyles-Ferris, who recently completed his PhD at the University of Leicester, said: “In most of the systems we’ve seen in the past, the star is completely destroyed. Swift J0230 is an exciting addition to the class of partially disrupted stars.”
The study’s lead author, Dr Phil Evans of the University of Leicester school of physics and astronomy, said: “This is the first time we’ve seen a star like our sun being repeatedly shredded and consumed by a low-mass black hole.”
Models of the Swift J0230 outburst suggest the star is of a similar size to the sun and is in an elliptical orbit around a low-mass black hole at the centre of its galaxy. Calculations indicate material equivalent to the mass of three Earths is ripped from Swift J0230’s atmosphere and heated up as it falls into the black hole.
The intense heat, around 2,000,000C, releases a huge amount of X-rays, which were first picked up by Nasa’s Neil Gehrels Swift Observatory.
The researchers estimate that the black hole is about 10,000 to 100,000 times the mass of the sun, which is small for a supermassive black hole.
Swift J0230 was spotted using a new tool – a transient detector – developed by the Leicester team for the observatory. Dr Kim Page from the university, who worked on the study, said: “Given that we found Swift J0230 within a few months of enabling our new transient-hunting tool, we expect that there are a lot more objects like this out there, waiting to be uncovered.”
