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black hole winds

Astronomers discover a super-fast star thrown out of the Milky Way

Many stars orbit near the Sagittarius A*, which is the super-massive black hole at the centre of the Milky Way galaxy. Some stars have been ripped apart when they got too close to the super-massive black hole. Other stars have changed colour due to the extremely high gravitational effects and in a few cases, the stars just slingshot into the intergalactic space like the S5-HVS1 star.

As reported in a paper available on the pre-print server arXiv, yet to be peer-reviewed, an international group of scientists have spotted a hypervelocity star as they were studying interesting objects for the Southern Stellar Stream Spectroscopic Survey(S5). The speed of hyper-velocity refers to a staggering 1,107 kilometres per second which is equivalent to 2.275 million miles per hour and could cover the distance between New York and Sydney in just 15.7 seconds.

There must be something that has accelerated to move the star at such high speed and a team of researchers are trying to estimate from where the star could most possibly come from. The most likely explanation based on their analysis is the core of the milky way which easily refers to the Sagittarius A*.

If the super-massive black hole is the real reason, then the star was probably kicked away with a velocity of more than 1800 kilometres per second and has been slowing down on its travel for about 4.8 million years. The star is a standard hydrogen fusing star or the main sequence object and is located close to 30,000 light-years from the Earth.

It is the fastest main sequence star which was ever discovered and it is not unique as astronomers have discovered dozens of stars like these and although many of such stars appear to have accelerated out of the galaxy by events other than the interactions with Sagittarius A*. Researchers are suggesting that if one of the two stars in a binary system goes supernova, it could be enough to push its companion beyond the disk of the Milky Way.

However, the stars are not only being kicked out as scientists have detected stars entering the galaxy from the smaller companions of Milky Way. They could have been also accelerated by a supernova or a supermassive black hole yet to be observed.

Journal Reference: arXiv