Black Hole Caught Red-Handed in a Stellar Homicide |
Astronomers have gathered the most direct evidence yet of a supermassive black hole shredding a star that wandered too close. NASA’s Galaxy Evolution Explorer, a space-based observatory, and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were among the first to help identify the stellar remains.
Supermassive black holes, weighing millions to billions times more than the Sun, lurk in the centers of most galaxies. These hefty monsters lay quietly until an unsuspecting victim, such as a star, wanders close enough to get ripped apart by their powerful gravitational clutches.
Astronomers have spotted these stellar homicides before, but this is the first time they can identify the victim. Using a slew of ground- and space-based telescopes, a team of astronomers led by Suvi Gezari of The Johns Hopkins University in Baltimore, Md., has identified the victim as a star rich in helium gas. The star resides in a galaxy 2.7 billion light-years away.
Her team’s results will appear in May 2 online edition of the journal Nature.
“When the star is ripped apart by the gravitational forces of the black hole, some part of the star’s remains falls into the black hole, while the rest is ejected at high speeds. We are seeing the glow from the stellar gas falling into the black hole over time. We’re also witnessing the spectral signature of the ejected gas, which we find to be mostly helium. It is like we are gathering evidence from a crime scene. Because there is very little hydrogen and mostly helium in the gas we detect, we know from the carnage that the slaughtered star had to have been the helium-rich core of a stripped star,” Gezari explained. continue reading