Clusters of thousands of stars can decay into clusters of dozens of stars black hole A new study found that in a billion years.
This dark fate may have arisen from the actions of some of the black holes that may currently reside within the star cluster, and this discovery could shed light on the future of dozens of similar clusters in the world. Bima SaktiThe researchers say.
Scientists analyze ball group, which is a cluster filled with old stars. Roughly spherical in shape, each may contain millions of stars. The Milky Way has more than 150 globular clusters arranged in a hemispherical circle around the galaxy.
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The researchers focused on Palomar 5, a globular cluster about 11.5 billion years old located on Aura bima sakti, about 65,000 light-years from Earth in the constellation Serpens.
Palomar 5 is one of the least known globular clusters. While the average ball mass is about 200,000 times sunscreen cream At about 20 light-years in diameter, Palomar 5 has a mass about 10,000 times the mass of the Sun, but a width of about 130 light-years, which makes it generally about 3,000 times smaller than average, said the study’s lead author, Mark Gillis. , an astrophysicist at the University. Barcelona in Spain, for Space.com.
At the same time, Palomar 5 is famous for its two long, flowing tails, made up of stars thrown by globular clusters. This amazing tail stretches over 22800 light years Its length – more than 20 degrees across the sky, or about 40 times the diameter of a full moon. Palomar 5 is one of the few known long-tailed star clusters, which makes it key to understanding how this tail formed.
Previous research has shown that the tail of Palomar 5 resulted from the way the Milky Way cracked the globular cluster. The gravitational pull of the galaxy is stronger on one side of Palomar 5 than on the other, tearing it apart – an extreme version of how the moon’s gravity causes tides on Earth. This so-called “tidal erosion” could help explain not only the tail of Palomar 5 but also the several dozen narrow stellar streams recently discovered in the Milky Way’s halo.
“I see Palomar 5 as a Rosetta stone that allows us to understand the composition of the river and study its origins,” Gillis said.
Scientists have suggested that Palomar 5 formed at a low density, which makes it easy tidal stripping to tear it apart and form its tail. However, a number of characteristics of its star suggest that it was once similar to a more massive globular cluster.
Now Gillis and colleagues suggest that Palomar 5 may indeed be more massive than it is today, and that its current scattered nature and long tail may be due to the presence of more than 100 black holes within it.
The researchers simulated the orbit and evolution of each star in Palomar 5 until the globular cluster finally disintegrated. They changed the initial characteristics of the simulated cluster until they found a good match with the actual observations of the cluster and its tails.
Scientists have found that the structure and tail of Palomar 5 may be due to a black hole that makes up about 20% of the mass of the globular mass. In particular, they suggest that Palomar 5 may currently have 124 black holes, each with an average mass of 17.2 times the mass of the Sun. Overall, that’s three times as many black holes as is currently thought from the mass of a sphere with that mass, Gillis said.
In this scenario, Palomar 5, like a typical globular cluster, consists of a black hole comprising only a fraction of its mass. However, gravity black holes dangling around stars that approach them, inflating their mass and making it easier for the Milky Way’s gravity to tear apart the stars. A billion years from now, they calculate that Palomar 5 may have expelled all of its stars, leaving only a black hole.
Gillis and his colleagues suggested that gravitational interactions within dense globular clusters could have prompted them to eject most of their black holes. Thus, dense globular clusters can retain most of their stars. Instead, the researchers found that initially less dense globular clusters, such as Palomar 5, might emit fewer black holes, and instead shed most of their stars. Thus, the black hole can completely dominate the globular cluster, and make up 100% of its mass.
“I’m so happy to finally understand why some groups are big, others are small,” Gillis said. “Many people assume that this is the result of a different channel of formation – namely nature. We show that appearance differences are due to evolution – upbringing.”
“Because Palomar 5 has many peculiar features that are also found in all other dense clusters, we were able to reconcile these results and hypothesize that Palomar 5 probably formed in a similar way to all the other clusters,” Gillis added.
The researchers found that when it came to the globular clusters in the Milky Way’s outer circle—that is, those farther from the galactic center than sun “It appears that half of the cluster is comparable to Palomar 5 and the other half is denser,” Gillis said. The researchers say that the Palomar 5-like half could face a similar fate dominated by black holes.
Gillis warns that they can create a model of Palomar 5 that does not contain a black hole and was not dense when it formed, but that also matches all the details that astronomers have seen. However, he says there is only a 0.5% chance the Palomar 5 formed this way.
“The ‘no black hole’ model is highly unlikely in nature, and it doesn’t solve the problem that Palomar 5 has similar properties to other dense clusters,” Gillis said.
The findings could help explain 10% of the Milky Way’s thin globular clusters such as Palomar 5, which has a mass less than 100,000 times the mass of the Sun but is more than 65 light-years in diameter. The researchers suggest that these thin globular clusters are rich in black holes and may eventually dissolve completely, giving rise to many streams of thin stars.
Future research could analyze Palomar 5 to learn more about its black hole, Gillis said.
Describe scientists in detail Their findings Online July 5 in Natural Astronomy.
Originally published on Space.com.
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