Astronomers have solved the mystery of a gargantuan cosmic explosion first spotted in March: A black hole did it, by killing and eating a star the size of our sun.
A couple months ago, we told you about an unusually bright and long-lasting blast of energyemanating from the center of a galaxy 3.8 billion light-years away in the constellation Draco. At first, astronomers thought it was a gamma-ray burst from a collapsing star, but when it kept shining in a variable pattern (brightening and fading) scientists realized it wasn’t your average GRB.
Astronomer Joshua Bloom at the University of California-Berkeley suspected it was a high-energy jet produced as a sun-sized star fell into a black hole and was torn to pieces. Bloom and researchers from several other institutions in the US and UK started analyzing data from the Swift Gamma Burst Mission, which first spotted the blaze of glory, as well as the Hubble Space Telescope, the Chandra X-ray Observatory and the Keck Observatory. Their analysis confirmed the theory, and was published Thursday in Science Express.
As tidal forces tear the star to pieces, some of the star’s mass is turned into energy. Some of that energy radiates as x-rays and gamma ray jets that spew from the swirling disk of star guts. The variable brightness is the result of new flares that occurred as more chunks of the destroyed star fell into the black hole, researchers said. Earth happened to be directly in the path of one of those gamma ray jets, which is why it looked so incredibly bright, scientists said.
By the way, this is still going on, more than two months later. Most star-death events last a matter of hours or maybe days, not weeks or months. (This star really died about 3.8 billion years ago.)