Hypervelocity star
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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, five 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.
[edit] List of HVS
- HVS 1 (SDSS J090745.0+24507) (a.k.a. The Outcast Star)
- HVS 2 (US 708)
- HVS 3 (HE 0437-5439) - possibly from the Large Magellanic Cloud
- HVS 4 (SDSS J091301.0+305120)
- HVS 5 (SDSS J091579.5+672238)
[edit] See also
[edit] External links
- A Successful Targeted Search for Hypervelocity Stars
- Two Exiled Stars Are Leaving Our Galaxy Forever
- An Unbound Hypervelocity Main-Sequence B-Type Star
- Entry in the Encyclopedia of Astrobiology, Astronomy, and Spaceflight
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