Astronomers catch a black hole shredding a star to pieces

October 21, 2015
This illustration of a recently observed tidal disruption, named ASASSN-14li, shows a disk of stellar debris around the black hole at the upper left. A long tail of ejected stellar debris extends to the right, far from the black hole. The X-ray spectrum obtained with NASA's Chandra X-ray Observatory (seen in the inset box) and ESA's XMM-Newton satellite both show clear evidence for dips in X-ray intensity over a narrow range of wavelengths. These dips are shifted toward bluer wavelengths than expected, providing evidence for a wind blowing away from the black hole. Credit: NASA/CXC/M. Weiss

When a star comes too close to a black hole, the intense gravity of the black hole results in tidal forces that can rip the star apart. In these events, called tidal disruptions, some of the stellar debris is flung outward at high speeds, while the rest falls toward the black hole. This causes a distinct X-ray flare that can last for years.

A team of astronomers, including several from the University of Maryland, has observed a tidal disruption event in a galaxy that lies about 290 million light years from Earth. The event is the closest tidal disruption discovered in about a decade, and is described in a paper published in the October 22, 2015 issue of the journal Nature.

"These results support some of our newest ideas for the structure and evolution of tidal disruption events," said study co-author Coleman Miller, professor of astronomy at UMD and director of the Joint Space-Science Institute. "In the future, tidal disruptions can provide us with laboratories to study the effects of extreme gravity."

The optical light All-Sky Automated Survey for Supernovae (ASAS-SN) originally discovered the tidal disruption, known as ASASSN-14li, in November 2014. The event occurred near a at the center of the galaxy PGC 043234. Further study using NASA's Chandra X-ray Observatory, NASA's Swift Gamma-ray Burst Explorer and the European Space Agency's XMM-Newton satellite provided a clearer picture by analyzing the tidal disruption's X-ray emissions.

"We have seen evidence for a handful of tidal disruptions over the years and have developed a lot of ideas of what goes on," said lead author Jon Miller, a professor of astronomy at the University of Michigan. "This one is the best chance we have had so far to really understand what happens when a black hole shreds a star."

After a star is destroyed by a tidal disruption, the black hole's strong gravitational forces draw in most of the star's remains. Friction heats this infalling debris, generating huge amounts of X-ray radiation. Following this surge of X-rays, the amount of light decreases as the stellar material falls beyond the black hole's event horizon—the point beyond which no light or other information can escape.

Gas often falls toward a black hole by spiraling inward and forming a disk. But the process that creates these disk structures, known as accretion disks, has remained a mystery. By observing ASASSN-14li, the team of astronomers was able to witness the formation of an accretion disk as it happened, by looking at the X-ray light at different wavelengths and tracking how those emissions changed over time.

The researchers determined that most of the X-rays are produced by material that is extremely close to the black hole. In fact, the brightest material might actually occupy the smallest possible stable orbit. But astronomers are equally interested to learn what happens to the gas that doesn't get drawn past the event horizon, but instead is ejected away from the black hole.

"The black hole tears the star apart and starts swallowing material really quickly, but that's not the end of the story," said study co-author Jelle Kaastra, an astronomer at the Institute for Space Research in the Netherlands. "The black hole can't keep up that pace so it expels some of the material outwards."

The X-ray data also suggest the presence of a wind moving away from the black hole, carrying stellar gas outward. However, this wind does not quite move fast enough to escape the black hole's gravitational grasp. A possible explanation for the low speed of this wind is that gas from the disrupted star follows an elliptical orbit around the black hole, and travels slowest when it reaches the greatest distance from the black hole at the far ends of this elliptical orbit.

"This result highlights the importance of multi-wavelength observations," explained study co-author Suvi Gezari, an assistant professor of astronomy at UMD. "Even though the event was discovered with an optical survey telescope, prompt X-ray observations were key in determining the characteristic temperature and radius of the emission and catching the signatures of an outflow."

Astronomers are hoping to find and study more events like ASASSN-14li so they can continue to test theoretical models about how black holes affect their nearby environments, while learning more about what do to any stars or other bodies that wander too close.

Explore further: Image: Black hole caught in a stellar homicide

More information: Flows of X-ray gas reveal the disruption of a star by a massive black hole, Nature, DOI: 10.1038/nature15708

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6 comments

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plasmasrevenge
1.5 / 5 (8) Oct 21, 2015
Re: "These results support some of our newest ideas for the structure and evolution of tidal disruption events"

It's just a filament of plasma, much like the ubiquitous filaments Herschel recently observed. Just a bit more current density. The narrative that this is due to tidal disruption is arrived at through an intense effort to avoid questioning foundational assumptions.
my2cts
1 / 5 (1) Oct 22, 2015
Black holes shredding things to pieces make me think of this:
https://www.youtu...6s6G8xig
jonesdave
4.1 / 5 (8) Oct 22, 2015
Re: "These results support some of our newest ideas for the structure and evolution of tidal disruption events"

It's just a filament of plasma, much like the ubiquitous filaments Herschel recently observed. Just a bit more current density. The narrative that this is due to tidal disruption is arrived at through an intense effort to avoid questioning foundational assumptions.


Jon M. Miller
Department of Astronomy, The University of Michigan, 1085 South University Avenue, Ann Arbor, Michigan 48103, USA.

So contact him and tell him why he's wrong. Instead of posting it here. Then the rest of us wouldn't have to put up with endless drivel from the EU/PC brigade, and their evidence-free nonsense.
cantdrive85
1.6 / 5 (7) Oct 22, 2015
Re: "These results support some of our newest ideas for the structure and evolution of tidal disruption events"

It's just a filament of plasma, much like the ubiquitous filaments Herschel recently observed. Just a bit more current density. The narrative that this is due to tidal disruption is arrived at through an intense effort to avoid questioning foundational assumptions.


Jon M. Miller
Department of Astronomy, The University of Michigan, 1085 South University Avenue, Ann Arbor, Michigan 48103, USA.

So contact him and tell him why he's wrong. Instead of posting it here. Then the rest of us wouldn't have to put up with endless drivel from the EU/PC brigade, and their evidence-free nonsense.

Yep, no one has ever seen a plasma filament before...dolt!

Not surprising you mindlessly and religiously believe in BH's that are truly evidence free. Scary BH monsters and magical fairy dust is your religion. Pathetic!
jonesdave
4.2 / 5 (5) Oct 22, 2015
Yep, no one has ever seen a plasma filament before...dolt!

Not surprising you mindlessly and religiously believe in BH's that are truly evidence free. Scary BH monsters and magical fairy dust is your religion. Pathetic!


So quote us the evidence, Einstein. How's your evidence-free b*llocks getting along? Still relying on Thornhill to figure out gravity for the scientifically illiterate wretches, are we?
Perhaps you'd like to present the qualifications of anybody that believes in that pseudoscience. Who are they, what are their qualifications?
It's garbage. Unadulterated garbage, at that. Scientifically illiterate pillocks believing scientifically illiterate pillocks. Zero evidence. End of. Bit like the electric comet sh*te.
How's that going, by the way?
bschott
1 / 5 (4) Oct 27, 2015
So quote us the evidence, Einstein. How's your evidence-free b*llocks getting along?


You need to remember that you are commenting under an article that claims a mathematical construct shredded a star. Symbols scribbled on a piece of paper aren't evidence regardless of what physics has convinced itself of.

It is no more valid than me writing down that God exists, then using the paper I wrote the words on as evidence that he does.

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