Astronomers ran simulations to predict the presence of two or three stellar-mass black holes in the Hyades open cluster.
An international team of astrophysicists discovered that the closest black holes to the Sun would be located in the Hyades star cluster, just 150 light years (45 parsecs) away. Previously, This record was held by the Gaia BH1 black hole, which is 480 parsecs from the Sun..
The astronomers ran computer simulations that tracked the motion and evolution of all the stars in the cluster and then compared them to the actual positions and velocities of the Hyades stars, which the European Space Agency’s (ESA) Gaia satellite has observed with absolute precision. The comparison allowed us to infer the existence of low-mass black holes, never before detected in this star cluster.
The missing pieces
The scientists determined that the properties of the Hyades observed today are best reproduced by simulations with two or three low-mass black holes (stellar mass black holes). They also showed that in a scenario where all the black holes have been ejected in the last quarter of the cluster’s age (approximately less than 150 million years ago) you can still find a good match. In this way they ensured that the evolution of the cluster could not erase the traces of its previous population of black holes.
“Our simulations can only simultaneously match the mass and size of the Hyades if some black holes are present in the center of the cluster today (or until recently),” explains Stefano Torniamenti, postdoctoral researcher at the University of Padua. (Italy) and main author of the article.
“This observation helps us understand how the presence of black holes affects the evolution of star clusters,” comments another of the authors, Mark Gieles, from the University of Barcelona (Spain). “These results also give us insight into how these mysterious objects are distributed throughout the galaxy.“. The results were recently published in Monthly Notices of the Royal Astronomical Society.