Black Gap Tears Aside Unfortunate Star – NASA Will get Unusually Shut View of Dramatic Destruction
A disk of scorching gasoline swirls round a black gap on this illustration. The stream of gasoline stretching to the precise is what stays of a star that was pulled aside by the black gap. A cloud of scorching plasma (gasoline atoms with their electrons stripped away) above the black gap is called a corona. Credit score: NASA/JPL-Caltech
NASA Will get Unusually Shut Glimpse of Black Gap Destroying a Star
Current observations of a
Once the star had been thoroughly ruptured by the black hole’s gravity, astronomers saw a dramatic rise in high-energy X-ray light around the black hole. This indicated that as the stellar material was pulled toward its doom, it formed an extremely hot structure above the black hole called a corona. NASA’s NuSTAR (Nuclear Spectroscopic Telescopic Array) satellite is the most sensitive space telescope capable of observing these wavelengths of light, and the event’s proximity provided an unprecedented view of the corona’s formation and evolution, according to a new study published in the Astrophysical Journal.
The work demonstrates how the destruction of a star by a black hole – a process formally known as a tidal disruption event – could be used to better understand what happens to material that’s captured by one of these behemoths before it’s fully devoured.
When a star wanders too near a black gap, the extreme gravity will stretch the star out till it turns into an extended river of scorching gasoline, as proven on this animation. The gasoline is then whipped across the black gap and is steadily pulled into orbit, forming a vivid disk. Credit score: Science Communication Lab/
Most black holes that scientists can study are surrounded by hot gas that has accumulated over many years, sometimes millennia, and formed disks billions of miles wide. In some cases, these disks shine brighter than entire galaxies. Even around these bright sources, but especially around much less active black holes, a single star being torn apart and consumed stands out. And from start to finish, the process often takes only a matter of weeks or months. The observability and short duration of tidal disruption events make them especially attractive to astronomers, who can tease apart how the black hole’s gravity manipulates the material around it, creating incredible light shows and new physical features.
“Tidal disruption events are a sort of cosmic laboratory,” said study co-author Suvi Gezari, an astronomer at the Space Telescope Science Institute in Baltimore. “They’re our window into the real-time feeding of a massive black hole lurking in the center of a galaxy.”
A Surprising Signal
The focus of the new study is an event called AT2021ehb, which took place in a galaxy with a central black hole about 10 million times the mass of our Sun (about the difference between a bowling ball and the Titanic). During this tidal disruption event, the side of the star nearest the black hole was pulled harder than the far side of the star, stretching the entire thing apart and leaving nothing but a long noodle of hot gas.
Scientists think that the stream of gas gets whipped around a black hole during such events, colliding with itself. This is thought to create shock waves and outward flows of gas that generate visible light, as well as wavelengths not visible to the human eye, such as ultraviolet light and X-rays. The material then starts to settle into a disk rotating around the black hole like water circling a drain, with friction generating low-energy X-rays. In the case of AT2021ehb, this series of events took place over just 100 days.
The event was first spotted on March 1, 2021, by the Zwicky Transient Facility (ZTF), located at the Palomar Observatory in Southern California. It was subsequently studied by NASA’s Neil Gehrels Swift Observatory and Neutron star Interior Composition Explorer (NICER) telescope (which observes longer X-ray wavelengths than Swift).
Then, around 300 days after the event was first spotted, NASA’s NuSTAR began observing the system. Scientists were surprised when NuSTAR detected a corona – a cloud of hot
Reference: “The Tidal Disruption Event AT2021ehb: Evidence of Relativistic Disk Reflection, and Rapid Evolution of the Disk–Corona System” by Yuhan Yao, Wenbin Lu, Muryel Guolo, Dheeraj R. Pasham, Suvi Gezari, Marat Gilfanov, Keith C. Gendreau, Fiona Harrison, S. Bradley Cenko, S. R. Kulkarni, Jon M. Miller, Dominic J. Walton, Javier A. García, Sjoert van Velzen, Kate D. Alexander, James C. A. Miller-Jones, Matt Nicholl, Erica Hammerstein, Pavel Medvedev, Daniel Stern, Vikram Ravi, R. Sunyaev, Joshua S. Bloom, Matthew J. Graham, Erik C. Kool, Ashish A. Mahabal, Frank J. Masci, Josiah Purdum, Ben Rusholme, Yashvi Sharma, Roger Smith and Jesper Sollerman, 15 September 2022, Astrophysical Journal.
DOI: 10.3847/1538-4357/ac898a
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