Some 250 million light-years away, in the center of another galaxy, a black hole swallowed a star that was too close. The phenomenon was recorded by several NASA telescopes and was the fifth closest example to Earth ever observed.
After the star was ripped apart by the black hole’s gravity, astronomers noted a “dramatic” increase in X-ray light around it, indicating that “as the star was pulled toward its destination, it formed an extremely hot structure on the black hole”. – The crown’.”
According to a new study published in the Astrophysical Journal, NASA’s NuSTAR satellite is the most sensitive space telescope capable of observing these wavelengths of light. The proximity of the phenomenon provided “unprecedented insight” into the formation and evolution of the corona.
in a sentenceNASA says this discovery demonstrates how the destruction of a star by a black hole, an event known as “tidal rupture,” can be used “to better understand what happens to captured material before it is swallowed whole.”
“Tidal disruption events are a kind of cosmic laboratory,” said study co-author Suvi Gezari, an astronomer at the Space Telescope Science Institute in Baltimore, quoted in the same note. “They are our window into the real-time transmission of a huge black hole lurking in the center of a galaxy.”
The phenomenon, dubbed AT2021ehb, and highlighted in this new study, occurred in a galaxy with a central black hole about 10 million times the mass of the Sun. During this “tidal disruption” event, the side of the star closer to the black hole it was pulled in more strongly, “stretching everything out and leaving only a long trail of hot gas.”
Scientists believe that during these events, the flow of gas swirls around the black hole and eventually collides with itself. “This is thought to create shock waves and external gas flows that generate visible light, as well as wavelengths not visible to the human eye, such as ultraviolet light and X-rays. The material then begins to settle into a disk which revolves around the black hole, with friction generating low-energy X-rays. In the case of AT2021ehb, this series of events occurred in just 100 days,” explains NASA.
The phenomenon was first detected on March 1, 2021 by the Zwicky Transient Facility (ZTF), located at the Palomar Observatory in southern California. It was later studied by NASA’s Neil Gehrels Swift Observatory and the Neutron Star Interior Composition Explorer (NICER) telescope.
About 300 days after first observing it, NuSTAR began to analyze the system, and scientists were surprised when the satellite detected a corona, that is, “a cloud of hot plasma.” With AT2021ehb there were no gas jets, making the corona discovery “unexpected”.
“We have never seen an X-ray emission event like this without the presence of a jet, and this is truly spectacular,” said Yuhan Yao, lead author of the new study. “Our AT2021ehb observations are in line with the idea that magnetic fields have something to do with how the corona forms, and we want to know what makes this magnetic field so strong.”
Source: TSF
