Before revision: Possible methods Hypervelocity stars Theorized in 1988, and observed in 2005, hypervelocity stars move faster than the escape velocity of the Milky Way, and are traveling out into intergalactic space.
After revision:  Theorized in 1988, and observed in 2005, hypervelocity stars move faster than the escape velocity of the Milky Way, and are traveling out into intergalactic space.