Hubble discovers a ravenous black hole twisting a captive star into a donut form

 

By Andrea Gianopoulos, NASA's Goddard Space Flight Center

These images by an artist demonstrate how a black hole can eat a star that is passing by. 1. A regular star travels close to a galaxy's supermassive black hole. 2. The black hole's gravitational field draws the star's outer gases in. 3. Tidal forces tear the star apart, shredding it. 4. The stellar remnants are attracted to the black hole in the form of a donut-shaped ring and will eventually fall into it, ejecting a massive amount of light and high-energy radiation. Leah Hustak, NASA, and ESA (STScI)

                                 Black holes don't hunt; they congregate. They wait patiently till an unfortunate star passes by. Once near enough, the star is severely torn apart by the black hole's gravitational pull and its gases are sloppily devoured while being belched forth in a powerful radiation field.

The last moments of a star before it is swallowed by a black hole have been meticulously captured by astronomers using NASA's Hubble Space Telescope.

"Tidal disruption events" are what these are known as. The language obscures the nuanced, unfiltered violence of a black hole encounter, though. There is a balance between the black hole's radiation ejecting material and gravity drawing in stellar matter. Black holes are messy eaters, in other words. Hubble is being used by astronomers to uncover the specifics of what transpires when an errant star falls into the gravitational void.

Since the devoured star is located at the galaxy's centre, ESO 583-G004, about 300 million light-years distant, Hubble is unable to capture the mayhem of the AT2022dsb tidal event up close. However, astronomers studied the light from the fragmented star, which includes hydrogen, carbon, and more, using Hubble's powerful ultraviolet sensitivity. Forensic information about the murder in the black hole is provided via spectroscopy.

Astronomers have identified about 100 tidal disruption events near black holes using a variety of equipment. On March 1, 2021, another black hole tidal disruption event was observed by many of NASA's high-energy space observatories, and it occurred in a different galaxy. Data was gathered in X-ray radiation, as opposed to Hubble observations, from an incredibly hot corona surrounding the black hole that emerged after the star had already been shattered.

"Given the observing duration, there are still incredibly few tidal occurrences that are visible in ultraviolet light. This is disappointing since the ultraviolet spectrum may provide a wealth of information, "said Emily Engelthaler of the Cambridge, Massachusetts-based Center for Astrophysics | Harvard & Smithsonian (CfA). "We're thrilled that we can learn more about what the debris is doing thanks to this information. We can learn a lot about a black hole from the tidal event." The dying star is undergoing changes on a time scale of days or months.

The star shredding is thought to occur just a few times per 100,000 years for any given galaxy with a quiescent supermassive black hole at its centre.

The All-Sky Automated Survey for Supernovae (ASAS-SN or "Assassin"), a network of ground-based telescopes that scans the extragalactic sky roughly once a week for violent, variable, and transient events that are shaping our universe, first discovered this AT2022dsb stellar snacking event on March 1, 2022. Because of how near and brilliant this intense collision was to Earth, Hubble researchers were able to conduct ultraviolet spectroscopy for a longer length of time than usual.

"These phenomena are typically difficult to witness. Perhaps a few observations are made when the disturbance first starts, when it is quite bright. Our software differs in that it is created to examine a few tidal occurrences over the course of a year to determine what occurs, "Peter Maksym from the CfA explained. "We detected this early enough to witness it during these really active periods of black hole development. The accretion rate decreased with time, eventually becoming a trickle."

According to the interpretation of the Hubble spectroscopic data, the former star is now a highly bright, hot, donut-shaped region of gas. A black hole is located in the centre of this region, which is the size of the solar system and is known as a torus.

"On the edge of that doughnut, we are searching. A stellar wind being thrown towards us from the black hole at a speed of 20 million miles per hour (three percent the speed of light) is sweeping across the planet "Maksym stated. "We are still trying to process the occurrence in our minds. The star is torn apart, and the resulting debris is entering the black hole. Thus, there are models that give you the impression that you understand what is happening, and then there is what you really see. At the nexus of the known and unknown, scientists might be in an exciting position."

The findings were presented during the American Astronomical Society's 241st conference in Seattle, Washington.