Scientists have finally solved the mystery behind the bizarre object floating in the center of the Milky Way Galaxy, according to a new study, putting to rest questions that have bugged them for years.
Astronomers have long been looking forward to the day our galaxy's supermassive black hole tears apart a passing cloud of hydrogen gas called G2 - so naturally they were disappointed at the lack of fireworks on its closest approach to Earth this past summer.
"G2 survived and continued happily on its orbit; a simple gas cloud would not have done that," study leader Andrea Ghez, a physics professor at UCLA, said in a statement. "G2 was basically unaffected by the black hole."
So if G2 isn't a ball of hydrogen gas, what is it? Researchers now believe that the mysterious object is in fact a pair of stars that smashed together to form one giant star, surrounded by a fog of gas and dust.
The findings about G2 are based on Keck telescope observations from Hawaii and were published Monday in The Astrophysical Journal.
Black holes are massive, invisible voids that consume anything and everything in their wake. They are so dense, not even light can escape their gravitational pull. However, their influence on nearby stars is visible and provides a signature, according to Ghez, who studied thousands of stars in the neighborhood of the Milky Way's black hole. And G2 appears to be just one of those stars near the black hole, created from its powerful gravity that can cause binary stars to merge into one. What's more, in our galaxy, massive stars primarily come in pairs.
"This may be happening more than we thought," added Ghez. "The stars at the center of the galaxy are massive and mostly binaries. It's possible that many of the stars we've been watching and not understanding may be the end product of mergers that are calm now."
G2 currently appears to be in the inflated stage, during which large objects near black holes become elongated. Likewise, G2's surface is being heated by neighboring stars, creating the observed enormous cloud of gas and dust surrounding it, masquerading itself as hydrogen gas.
"We are seeing phenomena about black holes that you can't watch anywhere else in the Universe," Ghez said. "We are starting to understand the physics of black holes in a way that has never been possible before."