Closest 'black hole' to earth has lost its status as one

WION Web Team New Delhi Oct 21, 2020, 10.09 AM(IST) Oct 21, 2020, 07.42 PM(IST)

Representative image Photograph:( Reuters )

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Everyone knows that there is a supermassive black hole at the centre of our galaxy. But that's too far away. There 'was' a black hole closer to home, about 1120 light-years away

Black holes are perhaps the most famous celestial bodies in popular culture. There are theories like black holes being portals of time travel, a passage to another universe etc. It's not surprising that the mysterious black holes hold great importance in popular perception.

Everyone knows that there is a supermassive black hole at the centre of our galaxy. But that's too far away. There 'was' a black hole closer to home, about 1120 light-years away. Now, a study has said that there may not be a black hole here at all.

Earlier hypothesis

It was considered that a binary star system HR 6819 had a black hole in it. But now, scientists have discovered that there is no black hole there at all.

One of the two stars in the system is a Be spectral type and the other is B3 III star. Both the stars were considered to have equal mass.

In a binary system, when two stars have equal mass, they orbit around each other. However, in this star system, it was observed that the Be spectral star was almost spinning in one place while the B3 III star was in orbit.

This defied the science of binary star systems having stars of equal masses. Both of these stars should have been in orbit. But they weren't

It was hence concluded that a black hole was exerting its gravitational effect on the star system and was holding Be spectral star in its place

The competing theory

This theory suggested that there was mistake in calculating masses of the stars and that they were NOT equal.

In reality, the theory said, the Be spectral star (which spun in one place) was bigger than B3 III star. Not only that, the bigger star took away huge chunk of stellar material off the smaller star.

If this was true then there should have been variations in the disc of Hydrogen gas being emanated from the bigger star.

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These variations have now been found

“This indicates that HR 6819 is a binary system consisting of a massive Be star and a low-mass companion that is the stripped-down remnant of a former mass donor star in a mass transfer binary,” wrote Douglas Gies and Luqian Wang, astronomers from Georgia State University.

They have hence concluded that there is no black hole in this binary star system. The title of nearest black hole from earth may hence be now changing hands.

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