A group of more than 100 large black holes hides in the heart of the Palomar 5 star cluster, located 76,000 light years from the Sun. According to research led by the University of Barcelona, the cluster formed more than 10,000 years ago. million years ago it concentrates huge black holes with a mass equivalent to twenty solar masses.
According to a press release , all black holes were born from late-life supernova explosions of massive stars, when the cluster was still very young. However, the concentration of black holes is unusual for this class of structures: more than 20% of the total mass of the stellar cluster is made up of black holes , when according to theoretical estimates this percentage should be much lower.
The Palomar 5 is a star cluster discovered by Walter Baade in 1950, and subsequently confirmed as an independent group through a new discovery of AG Wilson, in 1955. At first, Wilson called Serpens Globular Cluster.
THE METAMORPHOSIS OF PALOMAR 5
Currently, Palomar 5 is experiencing a strong gravitational influence from the Milky Way, which modifies its usual characteristics. Because of this, many of the stars that make it up are moving away from the cluster, creating tails in opposite directions that extend over a length of more than 13,000 light-years.
Star clusters or globular clusters are a spherical set of stars that usually orbits a galactic nucleus, with a behavior similar to that of a satellite orbiting a planet. Globular clusters specify the force of their union by the effect of gravity: this gives them spherical shapes and relatively high stellar densities over their central area.
According to the new study, published in the journal Nature Astronomy, streams of stars have recently been detected in the Milky Way’s halo, which have been expelled from globular clusters due to different changes and disturbances suffered by these clusters.
This is precisely what happens with Palomar 5, which on the one hand is being affected by the gravitational influence of the Milky Way and, at the same time, by the action of the overpopulation of black holes that it hosts.
A BLACK FUTURE
The scientists explained that globular clusters are formed by including a conventional population of black holes, which in normal situations would be around a third of that of Palomar 5.
However, when globular clusters advance in age, there is an increase in the elimination of stars, which leads to an imbalance: at the same time, the percentage of black holes increases gradually.
This is what is happening with Palomar 5, which according to the estimates of scientists is over 11 billion years old. Around 150 globular clusters similar to Palomar 5 are believed to orbit the Milky Way.
According to astronomers, the trend will continue until in the next billion years Palomar 5 becomes a cluster of black holes . At that time, the universe will be very different, and the striking features of this globular cluster will be commonplace today.