Why Our Galaxy’s Black Hole Didn’t Eat Mystery Object

Latest research suggests enormous black hole drove two binary stars to merge into one

Screenshot of a simulation depicting the G2 black hole encounter... before astronomers realized G2 isn't quite what it seemed. (Credit: LECHO/MPE/M. Schartmann/L. Calçada)

Screenshot of a simulation depicting the G2 black hole encounter before astronomers realized G2 isn’t quite what it seemed. (Credit: LECHO/MPE/M. Schartmann/L. Calçada, O’Neil)

Having studied it during its closest approach to the black hole this summer, UCLA astronomers believe that they have solved the riddle of the object widely known as G2. A team led by Andrea Ghez, professor of physics and astronomy in the UCLA College, determined that G2 is most likely a pair of binary stars that had been orbiting the black hole in tandem and merged together into an extremely large star, cloaked in gas and dust — its movements choreographed by the black hole’s power.

Telescopes at the Keck Observatory use adaptive optics, which enabled UCLA astronomers to discover that G2 is a pair of binary stars that merged together. (Credit:  Ethan Tweedie)

Telescopes at the Keck Observatory use adaptive optics, which enabled UCLA astronomers to discover that G2 is a pair of binary stars that merged together. (Credit: Ethan Tweedie)

Astronomers had figured that if G2 had been a hydrogen cloud, it could have been torn apart by the black hole, and that the resulting celestial fireworks would have dramatically changed the state of the black hole.

Ghez and her colleagues — who include lead author Gunther Witzel, a UCLA postdoctoral scholar, and Mark Morris and Eric Becklin, both UCLA professors of physics and astronomy — conducted the research at Hawaii’s W.M. Keck Observatory, which houses the world’s two largest optical and infrared telescopes.

Ghez said G2 now is undergoing what she calls a “spaghetti-fication” — a common phenomenon near black holes in which large objects become elongated. At the same time, the gas at G2’s surface is being heated by stars around it, creating an enormous cloud of gas and dust that has shrouded most of the massive star.

“We are seeing phenomena about black holes that you can’t watch anywhere else in the universe,” Ghez added. “We are starting to understand the physics of black holes in a way that has never been possible before.” (Credit: Stuart Wolpert)

via ucla

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