For years, astronomers have pondered the origins and the contents of the mysterious G2 object floating in the center of the Milky Way galaxy. Drifting towards the galaxy's supermassive black hole, the passing cloud was thought to be composed entirely of hydrogen gas, giving it the nickname "G2". But earlier this past summer researchers found that G2 had come in close contact with the black hole, and it survived-leading them on a new theory as to what the mysterious object could be.
Using the W.M. Keck Observatory in Hawaii, researchers at the University of California, Los Angeles led by Andrea Ghez found that the once believed cloud of hydrogen gas is far more than meets the eye.
"G2 survived and continues happily on its orbit" Ghez says. "A gas cloud would not do that. G2 was completely unaffected by the black hole-no fireworks, [nothing]."
Instead, the researchers now believe that the cloud of gas really is a pair of binary stars hidden by gas and dust as it approaches near the black hole. In spite of being cloaked in dust as it orbits the black hole's powerful gravitational field, hiding the true events that led to its survival, Ghez and her colleagues believe that the binary stars once moving in tandem merged to become a new, extremely supermassive star much like a new class of stars they're seeing at the epicenter of the black hole.
"G2 is not alone" Ghez says. "We're seeing a new class of stars near the [center of the Milky Way] as a consequence of the black hole."
Utilizing technology that Ghez herself helped pioneer, to correct for the distorting effects of the Earth's atmosphere to enhance precision of the Keck Observatory's imaging, the team was able to track G2 and hope to gain further information regarding its activity as it continues to move in orbit around the black hole. It's a field of our galaxy that researchers know little about and Ghez's research team hopes to further reveal the unique conditions and consequences of a black hole's presence.
In recent studies, Ghez and her colleagues have revealed many surprises to the field of astronomy in the region of our galaxy where the supermassive black hole exists, including: young stars in areas where they shouldn't be and disappearing old stars in places where they should still be. And using adaptive optics, they are even now seeing entirely new classes of stars unlike anything researchers have seen before.
"We are seeing phenomena about black holes that you can't watch anywhere else in the universe" Ghez says. "We are starting to understand the physics of black holes in a way that has never been possible before, and is possible only at the center of the galaxy."
