Hypervelocity stars. Brown et al. (2005, Astroph. J., 622, L33) found a “hyperve
ID: 3160975 • Letter: H
Question
Hypervelocity stars. Brown et al. (2005, Astroph. J., 622, L33) found a “hypervelocity” star, which is likely a B9 main sequence star traveling at 850 km s1 located 60 kpc from the Galactic center where it is thought to have originated1. Use reasonable assumptions to argue whether or not this star is bound to the Milky Way Galaxy.
info: It is argued that hypervelocity stars originate from an interaction with the massive black hole in the Galactic center.The massive black hole tidally disrupts a stellar binary when it falls within a distance such that the gravitational tidal force from the massive black hole exceeds the force that binds the binary. One of the stars will be ejected and one will be “captured” in a very close orbit around Sgr A* (which may explain the origin of stars like S2).
Explanation / Answer
hypervelocity are must be ejected from massive black holes.B-type stars are stars that are more massive and much more luminous than the Sun.this star ismoving away from us at 850 km/s.This is an absurd velocity.Stars near the Sun have relative motions of order 10 km/s. Stars in the halo have differenttypes orbits, with a dispersion around 100 km/s.
But 850 km/s makes this star the fastest moving main sequence star in the Galaxy outside the Galactic Center.
This star, though, is 110 kpc away, well beyond the normal confines of the Galaxy. In fact, the star is moving many times the velocity it needs to escape the Galaxy,forever.
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