US 708

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US 708 is one of the fastest moving stars in the Milky Way galaxy.[1] The star was first surveyed in 1982. Sloan Digital Sky Survey measured the star again in 2005. In 2015 Stephan Geier of the European Southern Observatory lead a team that published the star's velocity -- 1,200 kilometers per second.

The New York Times reported that the star's high velocity was originally suspected of being caused by the massive black hole at the center of the galaxy.[2] However, closer study suggested it had been one element of a pair of close binary stars. Its companion had already entered its White Dwarf stage when US 708 entered its Red Giant phase. Their respective orbits changed as its companion took gas from the outer layers of US 708. Then its companion acquired enough mass to go supernova, which triggered US 708 being flung away at its high velocity.

References

  1. "US 708: Hypervelocity Star Ejected by Supernova Breaks Galactic Speed Record". Science News. 2015-03-06. http://www.sci-news.com/astronomy/science-us708-hypervelocity-star-supernova-galactic-speed-record-02571.html. Retrieved 2015-03-10. "A multinational team of astronomers led by Dr. Stephan Geier from the European Southern Observatory in Garching, Germany, has determined that a hyper-velocity star known as US 708 is traveling at about 1,200 km per second." 
  2. {{cite news | url = http://www.nytimes.com/2015/03/10/science/fastest-star-in-the-galaxy-got-an-unusual-start.html | title = Fastest Star in the Galaxy Got an Unusual Start | publisher = [[New York Times | author = Douglas Quenqua | date = 2015-03-10 | page = D4 | location = | archiveurl = | archivedate = | accessdate = 2015-03-10 | deadurl = No | quote = By measuring the velocity, trajectory and rotation of the star, known as US 708, researchers at the European Southern Observatory determined that it started life as one half of a close binary pair — two stars that closely orbited one other. }}