When a star drifts too close to a black hole, it meets a grisly fate. The black hole stretches out the star and eventually swallows it up. The violent feeding frenzy is called a "stellar tidal disruption," according to NASA. The event generates a massive amount of energy and huge flares of high-energy radiation.
Previously, we didn't know much about tidal disruptions because it's hard to catch a black hole in the act of devouring a star. Now a team of researchers has captured how the dust surrounding black holes absorbs and reflects the flares produced by a tidal disruption.
Essentially, the researchers captured the first echoes of a black hole devouring a star.
Supermassive Black Hole Finder
Supermassive Black Hole Finder
SPACE - UNDATED: A Computer Simulated Image released by the NASA shows the gas from a star that is ripped apart by tidal forces as it falls into a black hole in Space. Some of the gas also is being ejected at high speeds into space. Using observations from telescopes in space and on the ground, astronomers gathered the most direct evidence yet for this violent process: a supermassive black hole shredding a star that wandered too close. NASA's orbiting Galaxy Evolution Explorer (GALEX) and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were used to help to identify the stellar remains. A flare in ultraviolet and optical light revealed gas falling into the black hole as well as helium-rich gas that was expelled from the system. When the star is torn apart, some of the material falls into the black hole, while the rest is ejected at high speeds. The flare and its properties provide a signature of this scenario and give unprecedented details about the stellar victim. To completely rule out the possibility of an active nucleus flaring up in the galaxy instead of a star being torn apart, the team used NASA's Chandra X-ray Observatory to study the hot gas. Chandra showed that the characteristics of the gas didn't match those from an active galactic nucleus. The galaxy where the supermassive black hole ripped apart the passing star in known as PS1-10jh and is located about 2.7 billion light years from Earth. Astronomers estimate the black hole in PS1-10jh has a mass of several million suns, which is comparable to the supermassive black hole in our own Milky Way galaxy. PHOTOGRAPH BY NASA / Barcroft Media /Barcoft Media via Getty Images
This artist's conception illustrates one of the most primitive supermassive black holes known (central black dot) at the core of a young, star-rich galaxy. (Photo by: Universal History Archive/UIG via Getty Images)
The Herschel Space Observatory has shown that galaxies with the most powerful, active, supermassive black holes at their cores produce fewer stars than galaxies with less active black holes. (Photo by: Universal History Archive/UIG via Getty Images)
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"This is the first time we have clearly seen the infrared light echoes from multiple tidal disruption events," Sjoert van Velzen, lead author on the new study, said in a statement.
After a tidal disruption, the high-radiation flares destroy most of the immediate surrounding dust particles. But farther out from the center of the black hole, the flares become less intense. Dust farther from the center gets heated by the flares, but not destroyed.
The heated dust gives off infrared radiation that telescopes can pick up. This is useful because astronomers can use the radiation signatures to get an idea of how much energy was created in the tidal disruption.
"Our study confirms that the dust is there, and that we can use it to determine how much energy was generated in the destruction of the star," co-author Varoujan Gorjian said in the statement.
The research will help scientists better understand tidal disruptions and what happens when stars stray too close to black holes.