Black hole found hidden in a star cluster

It was observed thanks to the Very Large Telescope of the European Southern Observatory (Vlt - Eso). This is the first time one has been discovered outside the Milky Way.

A black hole has been discovered in a star cluster. It is a unique case identified outside the Milky Way. To identify it was an international team led by Sara Saracino of the University of Liverpool John Moores in which also participated the Palermo Astronomical Observatory of the National Institute of Astrophysics (Inaf). The results of the study are being published in Monthly Notices of the Royal Astronomical Society. The analysis identified a black hole, with a mass 11 times that of the Sun, within the star cluster NGC 1850.

How the black hole was discovered in the star cluster

The black hole was detected thanks to the Very Large Telescope of the European Southern Observatory (Vlt - Eso). "A bit like Sherlock Holmes hunting a criminal by looking for his missteps, we observed every single star in this cluster with a magnifying glass to look for evidence of black holes without seeing them directly," Saracino recounted. The work has allowed us to verify that a black hole, in the star cluster NGC 1850, alters the orbit of a large star that is close to it.

What to expect from observing black holes

Until recently, observing black holes was impossible or at least very difficult. Only in recent years it has been possible to do so with certainty by recognizing the X-ray emissions that occur at certain stages or by gravitational waves produced when black holes merge with each other or incorporate a neutron star. The new method of Saracino's team opens new horizons on the observation of black holes.

To recognize the effects of black holes on the orbit of nearby stars have been collected data for about 2 years using the instrument Muse (Multi Unit Spectroscopic Explorer) installed on the Vlt telescope in the Chilean desert of Atacama. From the observation of light in every single star in the vicinity, they obtained information on thousands of stars until the discovery of the black hole.

The "black holes" are still a big rebus and there are many studies on how they are formed and what consequences they have in the cosmos. Recently a storm of black holes has been discovered that has upset the galaxy, while it has also been identified that they can trigger galactic tsunamis.

Stefania Bernardini