The closest black hole to the Earth has been discovered just 1,000 light years away — near enough to see its companion stars with the nake...
The closest black hole to the Earth has been discovered just 1,000 light years away — near enough to see its companion stars with the naked eye on a clear night.
Located in the constellation of Telescopium, the hole forms part of a so-called 'triple system — one named 'HR 6819' — with its two accompanying stars.
The presence of a hidden black hole in HR 6819 was discovered by researchers from the European Southern Observatory (ESO)'s La Silla Observatory in Chile.
The team used a 2.2 metre telescope to track the companion stars' motion — and reveal the influence of the black hole they orbit.
However, no telescope or binoculars are needed to see the stars from the Earth — and they are visible from the southern hemisphere by eye on a dark, clear night.
The closest black hole to the Earth has been discovered just 1,000 light years away — near enough to see its companion stars with the naked eye on a clear night. Located in the constellation of Telescopium, the hole form part of a so-called 'triple system — one named 'HR 6819' — with its two accompanying stars, as pictured
'We were totally surprised when we realised that this is the first stellar system with a black hole that can be seen with the unaided eye,' said paper author and astronomer Petr Hadrava of the Academy of Sciences of the Czech Republic in Prague.
The team originally observed HR 6819 system as part of a study of double-star systems.
In analysing their observations, however, they were stunned to discover a third, previously undetected body — the black hole.
The findings show that one of the two visible stars orbits an unseen object every 40 days, while the second star keeps a larger distance.
The hidden black hole in HR 6819 is one of the very first known stellar-mass black holes — formed by the collapse of a star — that does not interact violently with its environment and therefore appears truly black.
However, the team could spot its presence and calculate its mass by studying the orbit of the star that more closely orbits it.
'This system contains the nearest black hole to Earth that we know of,' said paper author and astronomer Thomas Rivinius.
'An invisible object with a mass at least four times that of the Sun can only be a black hole.'
The team believe that this triple system could lead to many more similar black holes being found in the future.
The presence of a hidden black hole in HR 6819 was discovered by researchers from the European Southern Observatory (ESO)'s La Silla Observatory in Chile, pictured. The team used a 2.2 metre telescope to track the companion stars' motion — and reveal the black hole
Astronomers have spotted only a couple of dozen black holes in our galaxy to date, nearly all of which strongly interact with their environment and make their presence known by releasing powerful X-rays.
Scientists estimate that, over the Milky Way's lifetime, many more stars should have collapsed into black holes at the end of their lives.
The team say that the discovery of a silent and invisible black hole in HR 6819 provides clues about where these other missing holes might be.
Astronomers also believe that the revelation could shine some light on a second system with two stars, called LB-1, which may also harbour a black hole.
'There must be hundreds of millions of black holes out there, but we know about only very few,' said Dr Rivinius.
'Knowing what to look for should put us in a better position to find them.'
The full findings of the study were published in the journal Astronomy & Astrophysics.
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