Evidence of 2nd
Black Hole in Milky Way
Ten
hypervelocity stars found shooting away from the
centre of the Milky Way has strengthened astronomers'' beliefs that the centre of our galaxy hosts a colossal Black Hole.
Astronomers believe there is a colossal Black Hole - weighing about 3.6 million times the Sun''s mass - at the centre of the Milky Way. But some contend there is also a second Black Hole there that weighs 1000 to 10,000 Suns.
While, to date the existence of a second Black Hole is inconclusive, astronomers say the
Evidence comes from observations of a cluster of young stars located just a fraction of a light year from the monstrous Black Hole - where gravitational forces should prevent any stars from forming.
Youjun
lu, an astrophysicist at the University of California in Santa Cruz, US, and colleagues say that finding a
pair of hypervelocity stars hurtling through space at 1000 km/sec or faster would be "definitive evidence" of the existence of two large Black Holes in the Milky Way.
Due to their orbit around each other, the two Black Holes would boast a wider sphere of influence on their surroundings than a single Black Hole. So if they were approached by a pair of stars that were quite close to each other (less than about a third the distance between the Sun and Earth), they would treat that stellar pair as a single star and shoot the pair outwards at hypervelocities.
That could not happen for a single Black Hole, since it would treat the stars as distinct individuals rather than a single unit, capturing one star and kicking out the other, said Lu.
"For a single black hole, the probability to eject a hypervelocity binary star is negligible," New Scientist quoted him as saying.
According to Lu, about 10 percent of the stars in the Sun''s neighbourhood have a close partner. So if that proportion is the same near the galactic centre, one of the 10 hypervelocity stars that have already been found may actually be a binary.
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