Abhay Singh
A star cluster named Palomar 5, existing in the vast expanse of the universe, could potentially conceal an extensive array of over 100 stellar-mass black holes within its enigmatic confines.
Identified as a stellar stream, Palomar 5 gracefully extends across a remarkable span of 30,000 light-years, weaving a celestial tapestry of stars within its cosmic bounds.
Situated at an awe-inspiring distance of approximately 80,000 light-years, this captivating cluster serves as a testament to the marvels and mysteries scattered throughout the cosmic landscape.
“Fossils” of the early universe
Due to their high age, globular clusters like the Palomar 5 are frequently referred to as “fossils” of the early universe. They are spherical, dense, and home to between 100,000 and one million extremely old stars. Within a cluster, all of these stars are born simultaneously.
Scientists know of over 150 globular clusters in our galaxy, the Milky Way. They are excellent for providing information on the dark matter content of their galaxies and the history of the universe due to their extraordinary age.
Lately, astronomers have also become interested in star streams, which are extended star rivers that cross the sky. This is due to the highly accurate mapping of our galaxy that the Gaia satellite observatory has been doing.
The question of how a stream of stars forms has been a source of scientific curiosity. Originally thought to be “disrupted star clusters,” astrophysicist Mark Gieles from the University of Barcelona in Spain stated in 2021.
He said “However, none of the recently discovered streams have a star cluster associated with them, hence we can not be sure. So, to understand how these streams formed, we need to study one with a stellar system associated with it.”
He also added “Palomar 5 is the only case, making it a Rosetta Stone for understanding stream formation and that is why we studied it in detail.”
“The number of black holes is roughly three times larger than expected”
Palomar 5 researchers examined the tidal stream and star dispersion to determine how the stars became part of the cluster. Due to research that suggests black holes may exist in the central areas of globular clusters and that any interaction with them can cause their orbits to be disrupted, they incorporated black holes in some of their simulations.
They discovered that the present creation of Palomar 5 might have been caused by the existence of a sizable number of stellar-mass black holes within it.
It is likely that orbital interactions sent the stars into the tidal stream and away from the cluster. There’s a chance that this increased the number of black holes.
Gieles said “The number of black holes is roughly three times larger than expected from the number of stars in the cluster, and it means that more than 20 per cent of the total cluster mass is made up of black holes,”
According to researchers, the cluster will totally disintegrate in about a billion years. The only objects in the cluster that would remain would be black holes orbiting the galactic center just before this occurs.
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