Science_afficionado writes: Astronomers have discovered a surprising new class of “hypervelocity stars” that are moving at more than a million miles per hour, fast enough to escape the gravitational grasp of the Milky Way galaxy. The 20 hyper stars are about the same size as the sun and, other than their extreme speed, have the same composition as the stars in the galactic disk. The big surprise is that they don't seem to come from the galaxy's center. The generally accepted mechanism for producing hypervelocity stars relies on the extreme gravitational field of the supermassive black hole that resides in the galaxy's core. So the discovery means that astrophysicists must come up with an entirely new method for speeding stars to hypervelocities.