Hubble finds a black hole twisting a star

This sequence of artist’s illustrations shows how a black hole can devour a star that has come close to it – NASA, ESA, LEAH HUSTAK (STSCI

Using the Hubble Space Telescope, astronomers have recorded in detail the final moments of a star when it is engulfed by a black hole.

Black holes are gatherers, not hunters. They lie in wait until a hapless star passes. When the star gets close enough, the black hole’s gravitational grip violently tears it apart, devouring its gases while spewing intense radiation. This is called a ‘tidal disruption event’. There is a balance between the gravity of the black hole that pulls in the stellar matter and the radiation that pushes the matter out. In other words, black holes are messy eaters. Astronomers are using Hubble to discover the details of what happens when a rogue star plunges into the gravitational chasm.

Hubble is unable to photograph the chaos of the tidal event AT2022dsb up close, as the chewed up star is nearly 300 million light-years away at the center of the galaxy ESO 583-G004. But astronomers used Hubble’s powerful ultraviolet sensitivity to study the shredded starlight, which includes hydrogen, carbon, and more. Spectroscopy provides forensic clues to the black hole homicide.

Astronomers have detected around 100 tidal disruption events around black holes using various telescopes. NASA recently reported that several of its high-energy space observatories detected another black hole tidal disruption event on March 1, 2021, and it happened in another galaxy. Unlike the Hubble observations, the data was collected in X-ray light from an extremely hot corona around the black hole that formed after the star had already torn apart.

“However, there are still very few tidal events that are observed in ultraviolet light given the observation time. This is truly unfortunate because there is a lot of information that can be gleaned from ultraviolet spectra,” Emily Engelthaler of the Center for Astrophysics | Harvard & Smithsonian (CfA). “We’re excited that we can get these details about what the debris is doing. The tidal event can tell us a lot about a black hole.” Changes in the doomed star’s condition are occurring on the order of days or months. For any given galaxy with a quiescent supermassive black hole at its center, stellar crushing is estimated to occur only a few times every 100,000 years.