Black holes are perhaps the strangest of all that is found in space.
The almost invisible regions are parts of spacetime where gravity is so strong that nothing, including light and other electromagnetic waves, has enough energy to escape.
Essentially, they suck in anything and everything within their vicinity, and warp time in a way that is not quite yet understood.
Black holes are found throughout the observable universe though few have been spotted anywhere near Earth — that is until scientists observed the ‘HR 6819 hole’.
Just 1,000 lightyears away from Earth — a mere quadrillion miles — in space terms, the distance is but a speck in time.
With three times the side of the Sun, it is close enough to Earth that, on a clear night from the southern hemisphere, it can be made out against the sky with the naked eye.
Astronomers from the European Southern Observatory (ESO) found it back in 2020 and have been observing it ever since, attempting to track its movement and makeup to further understand the mysterious regions.
Black holes are formed by collapsing stars, and the HR 6819 hole was located in the constellation Telescopium, which forms part of a “triple system” with two accompanying stars.
The team at ESO found evidence of the invisible objects when they tracked two companion stars using a 2.2-metre telescope at the institute’s La Silla Observatory in Chile.
Petr Hadrava, Emeritus Scientist at the Academy of Sciences of the Czech Republic in Prague and research co-author of the subsequent paper said at the time: “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.”
The team didn’t initially set out to find a black hole but rather wanted to observe double-star systems.
On analysing their observation results, they were surprised to find a third, previously undetected body which, after further assessment, they established to be a black hole.
They found that one of the two visible stars orbits an unseen object every 40 days, while the second star keeps a wide berth.
That unseen object is the black hole, one of the very first known stellar mass black holes that do not interact violently with its environment.
Because of this, it is truly invisible and appears a true colour of black, as opposed to the warped and sometimes lighter vicious black holes.
The team, able to just about spot it, were able to calculate its mass by studying the orbit of the star in the inner pair.
“This system contains the nearest black hole to Earth that we know of,” wrote study leader and ESO scientist Dr Thomas Rivinius in the paper.
“An invisible object with a mass at least four times that of the Sun can only be a black hole.”
Experts working on the findings hope that the formula may help to identify further triple systems and more in the Universe.
