Clusters of thousands of stars can melt into dozens of swarms Black Hole Over a billion years, new research has been discovered.
This dark fate can result from the action of some black holes that may currently be in the cluster, and this discovery is Milky Way, Researchers say.
Scientist analyzed Globular cluster, A dense collection of ancient stars. It is almost spherical, and each may contain up to millions of stars. The Milky Way has more than 150 globular clusters arranged in a nearly spherical halo around the galaxy.
Researchers focused on Palomar 5, a globular cluster about 11.5 billion years ago. Milky Way Hello, About 65,000 light-years from Earth in Serpens.
Palomar 5 is one of the most sparse and known globular clusters.The average globular cluster is about 200,000 times larger Sun mass Palomar 5, which is about 20 light-years in diameter, weighs about 10,000 times as much as the sun, but has a diameter of about 130 light-years, which is about one-third the average density as a whole. The author, university astrophysicist Mark Gilles, said. The University of Barcelona, Spain, told Space.com.
At the same time, Palomar 5 is known for its two long tails, which consist of stars shed by globular clusters.These magnificent tails span more than 22,800 Light year Length — 20 degrees or more across the sky, or about 40 times the apparent diameter of the full moon. Palomar 5 is one of the few known clusters with such a long tail and is the key to understanding how such a tail is formed.
Previous studies have suggested that the tail of Palomar 5 is due to the way the Milky Way shattered globular clusters. The attraction of the galaxy is stronger on one side of Palomar 5 than on the other and tears it apart. This is an extreme version of how the lunar gravitational pull causes tides on Earth. This so-called “tide stripping” may help explain the stream of dozens of narrow stars recently detected in the Milky Way halo, as well as the Palomar 5 tail.
“I think Palomar 5 is a Rosetta Stone that can help you understand the formation of streams and learn about their ancestors,” says Gieles.
Scientists say that Palomar 5 is formed at a low density, Tide stripping Tear it to form a tail. However, many properties of the star suggest that it once resembled a denser globular cluster.
Now, Gieles and his colleagues say that Palomar 5 is actually much denser than it used to be, and its current sparse nature and long tail may be due to more than 100 black holes lurking in it. Suggests.
Researchers simulated the orbit and evolution of each star in Palomar 5 until the globular cluster finally collapsed. They changed the initial properties of the simulated cluster until they matched the actual observations of the cluster and its tail.
Scientists have discovered that the structure and tail of Palomar 5 may be due to black holes, which make up about 20% of the mass of globular clusters. Specifically, they suggest that Palomar 5 may currently have 124 black holes, each of which averages about 17.2 times the mass of the Sun. Overall, this is three times more black holes than currently expected for globular clusters of that mass, Gieles said.
In this scenario, Palomar 5 is formed by black holes, which, like a typical globular cluster, consist of only a small percentage of its mass.However gravity Inflate the clusters of black holes hanging around the stars approaching them, making it easier for the gravity of the Milky Way to tear the stars apart. A billion years from now, they calculated that Palomar 5 might have released all the stars, leaving only a black hole.
Gieles and his colleagues suggest that gravitational interactions within dense globular clusters can drive them to emit most of the black holes. Thus, dense globular clusters may retain most of those stars. In contrast, researchers have found that initially low-density globular clusters, such as Palomar 5, emit less black holes and can drop most stars instead. As a result, black holes can take full control of such globular clusters and occupy 100% of their mass.
“I’m most excited to finally understand why some clusters are big and others are small,” said Gilles. “Many people simply assumed that this was a different formation channel, the result of nature. The difference in appearance was due to evolution, or nurturing.”
“Palomar 5 has some unique features that are also found in all other high-density clusters, so by adjusting these findings, Palomar 5 is probably formed in the same way as all other clusters. You can assume that, “Gieles added.
Researchers have learned about globular clusters in the outer halo of the Milky Way, that is, globular clusters far from the galactic center. Sun — “About half of the clusters seem to be comparable to Palomar 5, and the other half are denser,” Gieles said. Half similar to Palomar 5 may experience a dominance fate with similar black holes, researchers said.
Gieles warned that it was possible to devise a model of Palomar 5 that had no black holes, was not dense at the time of its formation, and matched all the details that astronomers saw. Still, he said, there is only a 0.5% chance that Palomar 5 was formed in this way.
“The“ no black hole ”model is very unlikely to occur in nature and does not solve the problem of Palomar 5 having similar characteristics to other high density clusters,” says Gieles.
These discoveries, which are less than 100,000 times the mass of the Sun, may help shed light on 10% of the fluffy Milky Way globular clusters, such as Palomar 5, with a diameter of more than 65 light-years. Researchers suggest that these fluffy globular clusters are rich in black holes and can eventually dissolve completely, resulting in many fine stellar streams.
Future research will be able to analyze Palomar 5 to learn more about black holes, according to Gieles.
Detailed scientist Their discovery Journal Nature Astronomy July 5th Online.
Originally published on Space.com.