Black holes are one of the most mysterious and fascinating phenomena in the universe. An article published in a journal Monthly Notices of the Royal Astronomical Society, It points to the existence of a large number of black holes in the Hyades cluster (the closest open cluster to our solar system), making them the closest black holes to Earth yet discovered.

The research is the result of a collaboration between a group of scientists led by Stefano Torniamenti from the University of Padua (Italy) and the important participation of ICREA Professor Mark Giles, Faculty of Physics, Institute of Space Sciences of the same university. Barcelona (ICCUB) and the Institute for Space Research of Catalonia (IEEC) and Friedrich Anders (ICCUB-IEEC).

The discovery specifically occurred during expert Stefano Torniamenti’s scientific stay at ICCUB, one of IEEC’s research units. A new study shows the potential existence of black holes in the Hyades cluster, positioning them as the closest black holes to Earth.

Black holes in the Hyades star cluster?

Since their discovery, black holes have been one of the most mysterious and fascinating phenomena in the universe and have become the object of study of researchers around the world. This is especially true for small black holes, as it has been observed during the detection of gravitational waves. Since the first gravitational waves were detected in 2015, experts have observed many events corresponding to the merger of pairs of low-mass black holes.

For the published study, the team of astrophysicists used simulations tracking the motion and evolution of all the stars in the Hyades, located approximately 45 parsecs, or 150 light-years, from the Sun, to recreate their current state.

Scattered clusters are loosely bound groups of hundreds of stars that share certain characteristics, such as age and chemical properties. The simulation results were compared with the actual positions and velocities of stars in the Hyades, which are now precisely known from observations made by the European Space Agency’s (ESA) Gaia satellite.

“Our simulations can simultaneously match the mass and size of the Hyads only if some black holes were present today (or until recently) at the center of the cluster,” says Stefano Torniamenti, a postdoctoral researcher at the University of Padua. author of the article.

The observed properties of Hyads can currently be best reproduced by simulations involving two or three black holes; but simulations in which all black holes were ejected (less than 150 million years ago, roughly the last quarter of the age of the cluster) may still be valid. A good fit because the evolution of the cluster could not erase traces of the previous black hole population.

The new results show that black holes originating from the Hyads are still within or very close to the cluster. This makes them the closest black hole to the Sun; much closer than the previous candidate (namely the Gaia BH1 black hole, which is 480 parsecs from the Sun).

In recent years, the breakthrough of the Gaia space telescope has made it possible for the first time to study in detail the positions and velocities of stars in the dispersed cluster and to confidently identify individual stars.

“This observation helps us understand how the existence of black holes affects the evolution of star clusters and contributes to the origin of gravitational wave sources of star clusters,” says Marc Giles, member of the Department of Quantum Physics and Astrophysics. University of Barcelona and lead first author. “These results also give us insight into how these mysterious objects are distributed across the galaxy.” Source