Hypervelocity star

From Wikipedia, the free encyclopedia

It has been suggested that Runaway_star be merged into this article or section. (Discuss)

Hypervelocity stars (HVSs) are stars moving with high velocity relative to the galaxy, which have or will eventually escape from the Galaxy, hence also the name Exiled Stars. Ordinary stars in the galaxy have velocities not exceeding 200 km/s, while hypervelocity stars are moving at several times this speed.

Currently, seven HVSs are known. One of them possibly originating from the Large Magellanic Cloud, this one discovered by H. Edelmann et al. Warren Brown from the Harvard-Smithsonian Center for Astrophysics discovered the first one in 2005. In 2006 two more have been discovered by Warren Brown et al. Their velocities are 558±12 and 638±12 km/s.

It is believed that around 1000 HVSs exist in our Galaxy. Considering the large number of stars in the Milky Way, this is only a tiny fraction.

HVSs are believed to originate by close encounters of binary stars to the black hole in the centre of the Milky Way. One of the two partners is captured by the black hole, while the other escapes with high velocity.