WHAT THE FAQ: How did astronomers find a black hole outside Milky Way and how far is it from Earth?

Recently, astronomers discovered a small, stellar-mass black hole outside the Milky Way Galaxy. According to Sara Saracino from the Astrophysics Research Institute of Liverpool John Moores University in the UK, who led the research team, the astronomers looked at every single star in this cluster with a magnifying glass to find some evidence that would point to the presence of black holes. Therefore, in today's FAQ, we try to find more about this recently discovered black hole outside the Milky Way Galaxy and break down what it means for us.

Where is the black hole hiding and how far is it from the Earth?
According to the astronomers' observations, the black hole is said to be hiding in the star cluster named NGC 1850 — one of the biggest star clusters in the Large Magellanic cloud. It is around 1,60,000 light years away from the Earth and estimated to be about 11 times the mass of the Sun. NGC 1850 is the second brightest star cluster and contains thousands of stars.  

How did the astronomers discover this black hole in the cluster of stars?
The astronomers used European Southern Observatory's Very Large Telescope in Chile to locate the hidden black hole. They noticed a star with a peculiar motion among this cluster of stars. Their investigation revealed that the gravitational influence came from a stellar-mass black hole. A specialised instrument on the VLT, the Multi-Unit Spectroscopic Explorer (MUSE) allowed the researchers to observe the very crowded star cluster and analyse the light of every single star.

Is there any specific method used by the astronomers to find out about the black hole?
The team used the detection method to reveal the presence of the black hole in NGC 1850 in the Magellanic cloud. They stated that the same method can help locate other black holes hidden in our galaxy as well as other galaxies too. 

What are the other methods used to detect black holes?
Usually, the astronomers detect black holes using the X-Ray glow of the holes they emit when they swallow matter or from the gravitational waves generated when black holes collide with one another. However, the smaller black holes don't emit any glow.