In 2010, scientists observed the flare that is the signature of a galaxy's central black hole shredding a star that wandered too close, and have identified both the black hole responsible and the "identity" of its unfortunate victim -- a star rich in helium gas.
"This is the first time we've actually been able to pinpoint what kind of star was disrupted," study lead author Suvi Gezari, an astronomer at Johns Hopkins University in Baltimore, told SPACE.com.
Such an event is rare, astronomers said, occurring just once every 10,000 years per galaxy.
Gezari and her colleagues monitored hundreds of thousands of galaxies in ultraviolet light and in June 2010 spotted a bright flare from a previously dormant black hole at the center of a galaxy about 2.7 billion light-years away.
"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," Gezari said. "We are seeing the glow from the stellar gas falling into the black hole over time."
The researchers analyzed the spectrum of the ejected gas, which revealed it was mostly helium.
"This is the first time where we have so many pieces of evidence, and now we can put them all together to weigh the perpetrator -- the black hole -- and determine the identity of the unlucky star that fell victim to it," Gezari said.
"These observations also give us clues to what evidence to look for in the future to find this type of event."