Ultrafast Stars Discovered Racing Through Milky Way

The galactic center is cloaked in a halo of dust that obscures all but the brightest stars from astronomers’ telescopes. But hypervelocity stars could provide a window into the star formation going on at the Milky Way’s dark heart. That’s because hypervelocity stars are thought to form when the supermassive black hole at the center of a galaxy devours one star in a binary system and ejects its twin, flinging it through space at superfast speeds, said study author Keith Hawkins, an astronomy student at Ohio University.
"These are incredibly fast-moving objects that are actually gravitationally unbound to the Milky Way," he said during the 221st annual meeting of the American Astronomical Society in Long Beach, Calif., last month.
Though these speed demons may be close to the black hole, they are not shrouded by dust and can be detected with telescopes. Because speedy rogue stars have been ejected from the galactic center, identifying them can reveal the types of star formation occurring there.
But until now, astronomers searching for these hypervelocity stars looked for bright, blue stars in locations where they weren’t supposed to form. Those stars, while easier to find, are typically three to four times as massive as our own sun, while most stars forming in other regions of the galaxy are the size of our sun or smaller, Hawkins said.