The voracious black hole consumes the equivalent of three Earth stars each time it passes

A star like our Sun in a nearby galaxy is gradually being devoured by a small but voracious black hole, losing the mass of three terrestrials each time it passes.

The discovery by astronomers at the University of Leicester was reported in Nature astronomy It provides the “missing link” in our knowledge about black holes that disturb the stars they orbit. It suggests a whole group of stars in the process of consumption that remain unknown.

Astronomers were alerted to the star by a bright flash of X-rays that appeared to be coming from the center of nearby galaxy 2MASX J02301709+2836050, about 500 million light-years away from the Milky Way. It, called Swift J0230, was observed when the process first occurred, using a new instrument developed by scientists at the Neil Gehrels Swift Observatory.

They quickly scheduled new observations of Swift, and found that instead of decaying as expected, it would glow brightly for 7 to 10 days and then suddenly turn off, repeating this process about every 25 days.

Similar behavior has been observed in so-called quasi-periodic flares and transient periodic nuclear phenomena, where the star has matter stripped away by a black hole as its orbit approaches it, but they differ in the number of times they erupt and whether this occurs in X-rays or in optical light. It is prevalent. The regularity of emissions from Swift J0230 falls somewhere between the two, suggesting that it forms the “missing link” between the two types of explosion.

Using proposed models of these two classes of events as a guide, scientists concluded that the Swift J0230 explosion represents a star similar in size to our Sun in an elliptical orbit around a low-mass black hole at the center of its galaxy. As the star’s orbit approaches the black hole’s intense gravitational pull, matter equivalent to the mass of three terrestrial planets is extracted from the star’s atmosphere and heated as it falls into the black hole.

The intense heat, around 2 million degrees Celsius, releases a huge amount of X-rays that were first captured by the Swift satellite.

Now you don’t see, now you see! X-ray images of the same location in the sky before (left) and after (right) the eruption of Swift J0230. These images were taken by the X-ray telescope on board the Swift satellite. Credit: Phil Evans (University of Leicester)/NASA SWIFT

Lead author Phil Evans, from the University of Leicester’s School of Physics and Astronomy, said: “This is the first time we have seen a star like our Sun repeatedly destroyed and consumed by a low-mass black hole.”

“So-called ‘partial and recurrent tidal disruption’ events are themselves a fairly new discovery, and seem to fall into two types: those that erupt every few hours, and those that erupt every year or so. This new regime falls in the gap In between, and when you crunch the numbers, you find that the types of objects involved also fit together perfectly.

Rob Isles-Ferris, who works with Dr. Evans on the SWIFT satellite, recently received his Ph.D. in Leicester, which included studying stars being disturbed by black holes. “In most of the systems we’ve seen in the past, the star has been completely destroyed,” he explains. Swift J0230 is an interesting addition to the class of partially disturbed stars, as it shows us that the two classes of these objects that have already been found are indeed related, with our new system giving us the missing link.

“Given that we found Swift J0230 just a few months after enabling our new transient hunting tool, we expect there to be many more objects like this out there,” said Kim Page from the University of Leicester, who analyzed data for the study. “.Waiting to be discovered.”

Dr Chris Nixon is a theoretical astrophysicist who recently moved from the University of Leicester to the University of Leeds. He led the theoretical interpretation of this event.

Researchers estimate that the black hole’s mass is about 10,000 to 100,000 times the mass of our Sun, which is very small for the supermassive black holes typically found at the centers of galaxies. The black hole at the center of our galaxy is thought to have a mass of 4 million solar masses, while most of it is located in a region with a mass of 100 million solar masses.

This is the first detection made using the new Swift satellite transient detector, developed by the University of Leicester team and running on their own computers. When an extreme event occurs, causing a burst of X-rays in an area of ​​the sky where there were no X-rays before, astronomers call it an astronomical X-ray transient, or at least it’s not a fast one – which is why a new tool has been developed to search for new types of transients in real time.

“This type of object was essentially undetectable until we built this new facility, and soon after we found this completely new, unprecedented event,” Evans adds. Swift is almost 20 years old and is suddenly faced with new events that we never knew existed. I think this shows that every time you find a new way to look at space, you learn something new and discover that there is something you didn’t know before.

Caroline Harper, Head of Space Science at the UK Space Agency, said: “This is another exciting, cutting-edge discovery from the Swift mission – a low-mass black hole that makes small ‘bites’ into a Sun-like star whenever it makes a discovery.” One revolves around it close enough.

“The UK Space Agency has been working in partnership with NASA on this mission for many years; the UK has led the hardware development of two pioneering scientific instruments, and we have provided funding for the Swift Science Data Centre, which we continue to support. We hope to receive further information from Swift about Gamma ray bursts across the universe, and the massive events they cause, in the future.