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A close encounter with another star put the doomed star – shown by the orange circle – on a path that took it near a supermassive black hole. The enormous gravity of the giant black hole stretched the star until it was torn apart.
Photo: Courtesy of NASA/CXC/M. Weiss; X-ray: NASA/CXC/MPE/S. Komossa et al.; optical: ESO/MPE/S. Komossa
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Hungry Black Hole Rips Star Apart
WASHINGTON – A big black hole ripped apart a sun-like star, gobbled a bit of it and flung the rest out into the cosmic neighborhood in an act of celestial gluttony caught by two orbiting observatories, scientists said Wednesday.
The doomed star probably went off course and into the supermassive black hole’s path after a close encounter with another star, according to astronomers who used NASA’s Chandra and the European Space Agency’s XMM-Newton X-ray observatories to capture the event.
Astronomers said a star about the size of our sun neared the black hole after veering off course following a close encounter with another star. The tremendous gravity of the black hole, estimated to have a mass 100 million times that of our sun, then stretched the star to the point of breaking.
Chandra and XMM-Newton observatories look at the cosmos by tracking X-rays, which means that they can peer through the cosmic gas and dust to detect things that optical telescopes cannot see.
These two observatories indicated that the outburst was caused when gas from the ripped-up star was heated millions of degrees as part of it was pulled into the black hole.
Some fraction of the star – more than 1 percent, less than 25 percent – was drawn into the black hole, while the rest of it was dispersed into the surrounding galaxy, the astronomers said at the briefing.
The force that dragged the star to its death is an extreme example of what is known as tidal disruption, the same kind of gravitational pull that the moon exerts on big bodies of water on Earth.
Tidal disruption of a star probably happens about once every 10,000 years in a typical galaxy, the scientists said. And a star that wanders close to a black hole is not necessarily dismembered and partially eaten, they said.
Some could be swallowed whole, while others might be forced to spin exponentially faster than their normal rotation rate.
This event happened far from Earth in the constellation Virgo, but could have implications for our Milky Way, which, like most galaxies, harbors a big black hole in its heart.
However, our sun lies fairly far from the galactic center, some 25,000 light-years away, and recent surveys indicate that there are no stars close enough to the Milky Way’s black hole to be dragged into its maw.
“None of the stars that we currently see at the center of our galaxy is in immediate danger of being swallowed,” Filippenko said.
The powerful X-ray blast that drew the attention of astronomers to the event first was seen in 1992 and remains visible as it fades, said Chandra press scientist Peter Edmonds, of the Harvard-Smithsonian Center for Astrophysics.