The Hyades cluster is the nearest open cluster to our solar system, and a publication in the journal Monthly Notices of the Royal Astronomical Society suggests the existence of several black holes there, making them the closest black holes to Earth yet discovered.
The study is the result of a partnership between a team of researchers from the University of Padua (Italy) and the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), the Institute of Space Studies of Catalonia (IEEC), and Friedrich Anders (ICCUB-IEEC), who also made significant contributions. The study was led by Stefano Torniamenti, from the University of Padua.
The discovery specifically happened while expert Stefano Torniamenti was conducting a study at the ICCUB, one of the research centers that makes up the IEEC.
Black holes in the Hyades star cluster?
Since their discovery, black holes have emerged as one of the universe’s most enigmatic and interesting phenomena, attracting the attention of scientists from all over the world. Small black holes have been discovered during the detection of gravitational waves, therefore this is especially true for them. Many occurrences that are associated with the mergers of low-mass black hole pairs have been seen by specialists since the discovery of the first gravitational waves in 2015.
The astrophysicists utilized simulations to recreate the current status of all the stars in the Hyades, which are approximately 150 light-years or 45 parsecs from the sun, for the study that was recently published.
Open clusters are loosely coupled collections of dozens to hundreds of stars that are similar in terms of their age and chemistry. The outcomes of the simulation were contrasted with the precise positions and velocities of the stars in the Hyades, which have since been determined through measurements by the European Space Agency’s (ESA) Gaia spacecraft.
“Our simulations can only match the mass and size of the Hyades simultaneously if some black holes are present at the center of the cluster today (or until recently),” says Stefano Torniamenti, a postdoctoral researcher at the University of Padua and first author of the work.
Although simulations, where all the black holes have been ejected (less than 150 million years ago, roughly the last quarter of the cluster’s age), can still provide a good match, the observed properties of the Hyades are best reproduced by simulations with two or three black holes at the moment. This is because the cluster’s evolution was unable to completely erase the traces of its previous black hole population.
The latest findings suggest that the Hyades-born black holes are still present within or very near the cluster. They are now significantly closer to the sun than the last contender (the black hole Gaia BH1, which is 480 parsecs away), making them the nearest black holes.
The development of the Gaia space telescope in recent years has made it possible to confidently identify individual stars and investigate the position and motion of open cluster stars in great detail for the first time.
The first author’s host in Barcelona was Mark Gieles, a professor in the UB Department of Quantum Physics and Astrophysics. “This observation helps us understand how the presence of black holes affects the evolution of star clusters and how star clusters in turn contribute to gravitational wave sources,” he says. These findings also shed light on the distribution of these enigmatic objects around the galaxy.
