February 8, 2012
Milky Way’s Black Hole Is Snacking On Asteroids
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NASA said on Wednesday that the giant black hole at the center of our Milky Way galaxy may be consuming asteroids.
They studied a cloud around the supermassive black hole known as Sagittarius A* (Sgr A) using NASA's Chandra X-ray Observatory.
Chandra has detected X-ray flares about once a day from the black hole for the past several years. The flares also have been seen in infrared data from ESO's Very Large Telescope in Chile.
Researchers said asteroids passing within 100 million miles of the black hole would be torn into pieces by the tidal forces of it.
The researchers found that the fragments from the asteroid are vaporized by friction as they pass through the hot, thin gas flowing onto Sgr A*. This produces a flare, and the remains of the asteroid are swallowed by the black hole.
NASA said this effect is similar to a meteor heating up and glowing as it falls through Earth's atmosphere.
"An asteroid's orbit can change if it ventures too close to a star or planet near Sgr A*," co-author Sergei Nayakshin, of the University of Leicester, said in a press release. "If it's thrown toward the black hole, it's doomed."
The team believes it would take asteroids larger than about six miles in radius to generate the flares observed by Chandra. They also said Sgr A* may be consuming smaller asteroids, but these would be difficult to spot because of how faint the flares would be.
"As a reality check, we worked out that a few trillion asteroids should have been removed by the black hole over the 10-billion-year lifetime of the galaxy," co-author Sera Markoff of the University of Amsterdam in the Netherlands said in a press release. "Only a small fraction of the total would have been consumed, so the supply of asteroids would hardly be depleted."
Asteroids are not the only thing Sagittarius A* would be able to consume. Planets thrown into orbits too close to the black hole would be doomed as well.
"This would be a sudden end to the planet's life, a much more dramatic fate than the planets in our solar system ever will experience," Kastytis Zubovas of the University of Leicester in the United Kingdom, and lead author of the report, said in a press release.
The research was published in the Monthly Notices of the Royal Astronomical Society.
Image 1: Asteroid heading towards black hole (artist impression). Credit: NASA/CXC/M.Weiss
Image 2: Supermassive black hole Sagittarius A* at the center of the Milky Way. (X-ray: NASA/CXC/MIT/F. Baganoff et al.; Illustrations: NASA/CXC/M.Weiss)
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