- Runaway star
A runaway star is one which is moving through space with an abnormally high
velocity compared to other stars around it. The velocity issupersonic relative to the surroundinginterstellar medium . Theproper motion of a runaway star often points exactly away from astellar association , whose member it therefore once must have been before it was hurled out.Possible mechanisms
Two possible mechanisms may give rise to a runaway star:
* In the first scenario, a close encounter between two binary systems may result in the disruption of both systems, with some of the stars being ejected at high velocities.
* In the second scenario, asupernova explosion in amultiple star system can result in the remaining components moving away at high speed. While both mechanisms are theoretically possible, astronomers generally favour the supernova hypothesis as more likely in practice.Examples
One example of a related set of runaway stars is the case of
AE Aurigae ,53 Arietis andMu Columbae , all of which are moving away from each other at velocities of over 100 km/s (for comparison, theSun moves through the galaxy at about 20 km/s faster than the local average). Tracing their motions back, their paths intersect near to theOrion Nebula about 2 million years ago.Barnard's Loop is believed to be the remnant of the supernova that launched the other stars.Another example is the X-ray object
Vela X-1 , where photodigital techniques reveal the presence of a typical supersonic bow shock hyperbola.External links
* [http://www.eso.org/outreach/press-rel/pr-1997/pr-01-97.html ESO press release about runaway stars]
* [http://www.daviddarling.info/encyclopedia/R/runawaystar.html Entry in the Encyclopedia of Astrobiology, Astronomy, and Spaceflight]References
* Blaauw A., Morgan W.W. (1954), "The Space Motions of AE Aurigae and mu Columbae with Respect to the Orion Nebula", Astrophysical Journal, v.119, p.625
* Hoogerwerf R., de Bruijne J.H.J., de Zeeuw P.T. (2000), "The Origin of Runaway Stars", Astrophysical Journal, v. 544, p.L133ee also
*
Hypervelocity star
*High-velocity star
Wikimedia Foundation. 2010.
