While some stars reach the end of their lives in an explosion and turn into a supernova, others end up getting rid of their material before it contracts, cools and extinguishes. But they rarely suffer a more serious fate, when they are devoured by a “hungry” black hole.
Such a thing only happens a few times every 100,000 years in a galaxy that contains a dormant black hole at its center. One of them was recently discovered by the Hubble Space Telescope. The researchers observed the last stage in the life of a star that passed near a black hole, which was about 300 million light-years away, and was being devoured, and it had emitted light in a so called event.AT2022DSB“according to The Verge.
The tearing up of a star by the black hole is called a “tidal disturbance event” (Tidal Distribution Event)، It is caused by the enormous gravitational forces of a supermassive black hole. These supermassive black holes lie at the centers of galaxies, and they can pull layers of gas from any star that gets too close, eventually shredding the star completely and pulling its remains into a disk around the black hole called the accretion disk, from which the black hole feeds.
At the American Astronomical Society meeting last Thursday, researcher Emily Engelthaler of the Harvard-Smithsonian Center for Astrophysics said: “Black holes are very messy eaters. They eat this accretion disk — this doughnut thing — from the inside, and they eat a lot and emit radiation as they go. With that, it makes this accretion disc swell into a nice big cake.”
This, and the researchers used the “Hubble” telescope to look at the ultraviolet radiation coming from the star, using a technique called spectroscopy to divide this light and find out what was swallowed. This allows them to see what kind of elements are present, and build clues about what’s going on inside the chaos around the black hole.
Such events are not usually observed, because ultraviolet rays do not pass easily in the atmosphere; Hence, it is difficult to collect data on it. Therefore, Engelthaler points out that a telescope outside the atmosphere should be used to record and study this rare event.
The researchers wanted to know how the star and the black hole changed over time, so they made a series of observations over the course of several months. They found that the temperatures in the disk dropped over time, and that the stellar wind moved away from the event, as it was traveling at huge speeds of 20 million miles per hour. or 3 percent of the speed of light.
However, the spectra collected by the researchers were not stable and varied greatly over time. This could simply be due to the remoteness of the source under consideration; So the signal became hidden among the noise. Or it could be that the circulating material around the black hole was thinner, and the amount of material the black hole pulled in decreased.