HYPERVELOCITY STAR

'Hypervelocity stars' ('HVS's) are stars with a velocity so great, that they are able to escape the graviational pull of the galaxy. Hence also the name ''Exiled Stars''. Ordinary stars in the galaxy have velocities on the order of 100 km/s, while hypervelocity stars (especially near the center of the galaxy, which is where they are "produced"), have velocities on the order of 1000 km/s.
HVSs were first theorized by J. Hills in 1988. Currently, nine HVSs are known. One of them possibly originated from the Large Magellanic Cloud, and was discovered by H. Edelmann et al. Warren Brown et al. from the Harvard-Smithsonian Center for Astrophysics discovered the first one in 2005. In 2006 two more were discovered by Warren Brown et al. Their velocities are 558±12 and 638±12 km/s (note that their velocities are less than 1000 km/s because they are many parsecs away from the center of the galaxy).
It is believed that about 1000 HVSs exist in our Galaxy. Considering that there are around 100 billion stars in the Milky Way, this is only a tiny fraction.
The main production method for HVSs is summarized as thus: they are believed to originate by close encounters of binary stars with the supermassive 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. Also, it is worth noting that "captured" does not mean swallowed, for in all likelihood the companion to the HVS will never fall into the black hole.

Contents

List of HVSs

See also

External links

List of HVSs

★ HV 1 - (J090744.99+024506.8) (a.k.a. The Outcast Star)

★ HV 2 - (SDSS J093320.86+441705.4) ''or'' (US 708)

★ HV 3 - (HE 0437-5439) - possibly from the Large Magellanic Cloud

★ HV 4 - (SDSS J091301.00+305120.0)

★ HV 5 - (SDSS J091759.42+672238.7)

★ HV 6 - (SDSS J110557.45+093439.5)

★ HV 7 - (SDSS J113312.12+010824.9)

See also

★ Runaway star

★ n-body problem

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

★ Hypervelocity stars. I. The spectroscopic survey information on HV 6 & HV 7