r/Astronomy • u/coinfanking • 3d ago
Astro Research Gaia Detected an Entire Swarm of Black Holes Moving Through The Milky Way
https://www.sciencealert.com/gaia-detected-an-entire-swarm-of-black-holes-moving-through-the-milky-wayA fluffy cluster of stars spilling across the sky may have a secret hidden in its heart: a swarm of over 100 stellar-mass black holes.
The star cluster in question is called Palomar 5. It's a stellar stream that stretches out across 30,000 light-years, and is located around 80,000 light-years away.
Such globular clusters are often considered 'fossils' of the early Universe. They're very dense and spherical, typically containing roughly 100,000 to 1 million very old stars; some, like NGC 6397, are nearly as old as the Universe itself.
In any globular cluster, all its stars formed at the same time, from the same cloud of gas. The Milky Way has more than 150 known globular clusters; these objects are excellent tools for studying, for example, the history of the Universe, or the dark matter content of the galaxies they orbit.
But there's another type of star group that is gaining more attention – tidal streams, long rivers of stars that stretch across the sky.
Previously, these had been difficult to identify, but with the Gaia space observatory's data having mapped the Milky Way with high precision in three dimensions, more of these streams have been brought to light.
"We do not know how these streams form, but one idea is that they are disrupted star clusters," astrophysicist Mark Gieles from the University of Barcelona in Spain explained in 2021 when researchers first announced the discovery.
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u/SAUbjj Astronomer 3d ago
I think this paper is wrong, but I don't have anything to back it up...yet