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article imageNASA's Chandra detects Milky Way's black hole devours asteroids

By JohnThomas Didymus     Feb 11, 2012 in Science
NASA astronomers say a supermassive black hole called Sagittarius A* at the center of the Milky Way may be vaporizing and devouring asteroids. This, the experts say, could explain the frequent flares observed in the center of the Milky Way.
The conclusion is based on data collected by NASA's Chandra X-ray Observatory. NASA reports Chandra has detected X-ray flares occurring about once a day from the supermassive black hole Sagittarius A* (Sgr A*). The brightness of the flares range from a few to nearly one hundred times that of a black hole.
NASA reports that the lead author of the report that appeared in the Monthly Notices of the Royal Astronomical Society, Kastytis Zubovas of the University of Leicester in the U.K., said, "People have had doubts about whether asteroids could form at all in the harsh environment near a supermassive black hole. It's exciting because our study suggests that a huge number of them are needed to produce these flares."
Peering into the heart of darkness - Sagittarius A*
Peering into the heart of darkness - Sagittarius A*
NASA
Zubovas and his colleagues suggest there is a cloud around Sgr A* that contains asteroids and comets which were stripped from their parent stars. According to the scientists, any asteroid passing within 100 million miles of the black hole, approximately the distance between Earth and the Sun, would be ripped apart by tidal forces produced by the gravitational field of the black hole and its fragments vaporized as the asteroid travels in hot, thin gas. The process produces a flare as the asteroid falls into the black hole.
According to NASA, co-author of the paper Sergei Nayakshin of the University of Leicester, said: "An asteroid's orbit can change if it ventures too close to a star or planet near Sgr A*. If it's thrown toward the black hole, it's doomed."
This image was taken with NASA s Chandra X-Ray Observatory. Ellipses indicate light echoes.
This image was taken with NASA's Chandra X-Ray Observatory. Ellipses indicate light echoes.
NASA
The scientists say that the flares detected by Chandra come from asteroids larger than about six miles in radius. Flares from asteroids smaller than six miles in radius would be undetected by Chandra, so the number of asteroids being devoured by the supermassive black hole may be much larger than is being detected, and the number of asteroids around SgrA* may number in trillions.
NASA reports co-author Sera Markoff of the University of Amsterdam in the Netherlands, said: "As a reality check, we worked out that a few trillion asteroids should have been removed by the black hole over the 10 million-year lifetime of the galaxy. Only a small fraction of the total would have been consumed, so the supply of asteroids would hardly be depleted."
Chandra X-ray Observatory sits inside the payload bay of Space Shuttle Columbia  waiting for the doo...
Chandra X-ray Observatory sits inside the payload bay of Space Shuttle Columbia, waiting for the doors to close.
NASA
Any planet whose orbit comes too close to the supermassive black hole would also fall into the black hole, but because there are much fewer planets than asteroids such events would occur only very occasionally. The scientists suggested that an incident involving a planet may have caused the significant X-ray flare of Sgr A* about a century ago, before X-ray telescopes were built. According to the scientists, Chandra and other X-ray missions have detected X-ray echoes of the flare they believe might have involved a planet swallowed by the supermasssive black hole. Such event, according to the scientists, is a very dramatic way for a planet to end its life.
Further observations of Sgr A* are being made to determine the frequency and brightness of flares. The information is expected to help improve understanding of how asteroids and planets are formed in environments dominated by supermassive black holes.
More about NASA, Chandar Xray observatory, Milky way, Asteroids
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