The two closest black holes to Earth have been discovered. Both the black holes are located in the Milky Way galaxy, and are of a new kind.
The European Space Agency’s (ESA’s) Gaia mission helped discover this new family of black holes by tracking the orbits of some stars.
1/ 🕳️🕳️ @ESAGaia has discovered the two closest black holes to Earth ever found!
This discovery alludes to a new family of #blackholes which is invisible, relatively ‘close-by’ and has stellar companions in large orbits around them ✨https://t.co/6cIfUGMmfU#GaiaMission pic.twitter.com/y2qlJpa67R
— ESA Science (@esascience) March 30, 2023
A team of astronomers studied these orbits and noticed that some of the stars ‘wobbled’ in the sky, according to the ESA. This implies that the stars were being gravitationally influenced by massive objects.
Other telescopes looked for the objects that influenced the stars, but could not find any light. This led astronomers to conclude that the objects are black holes.
What are the black holes called? How far are they from Earth?
The new family of black holes resides in Earth’s cosmic backyard. ESA states that many more black holes may be lurking in the shadow.
The black holes are called Gaia BH1 and Gaia BH2.
Gaia BH1 is the closest black hole to Earth, and is located 1,560 light years from the planet in the direction of the constellation Ophiuchus. Gaia BH2 is the second-closest black hole to Earth and is located 3,800 light years from the planet in the constellation Centaurus.
How were the black holes discovered?
Astronomers discovered the two black holes by studying the movement of their companion stars. Since there was a strange ‘wobble’ in the movement of the stars in the sky, it was implied that they were orbiting a very massive object.
The objects did not seem to emit any light, and hence, astronomers ruled out the possibility of them being double-star systems.
All black holes found so far have been discovered by the emission of light, usually at X-ray and radio wavelengths. The light is emitted by the material falling into a black hole.
What makes the two black holes unique?
The new black holes are unique because they are truly black, and can only be detected by their gravitational effects.
Another unique characteristic of this new family is that the distances of the stars to the respective black holes, and the orbits of the stars around the black holes, are much longer than the distances and orbits of any other known binary systems of black holes and stars.
Star-black hole pairs in which the star and black hole are close to each other are called X-ray binaries. These pairs are very bright and emit X-ray and radio light, making it easier to find them.
The two newly discovered black holes suggest that colossal behemoths in wider binaries are more common.
