According to some researchers, the oldest of these stars is 1.5 billion years old, while the youngest is only 100 million years old. paper Published in Astrophysics Journal Letter.
This infrared image from Hubble shows the Milky Way Core Cluster, the densest and most massive star cluster in our galaxy. Image credit: NASA / ESA / Hubble Heritage Team / STScI / AURA / T. Do & A. Ghez, UCLA / V. Bajaj, STScI.
The center of our Milky Way galaxy is located about 27,000 light-years away in the constellation Sagittarius and is a crowded place.
This region is so dense that it’s equivalent to a million stars crammed into the space between the Sun and Alpha Centauri, 4.3 light-years away.
This nuclear cluster surrounds Sagittarius A*, a 4.3 million solar mass black hole at the center of the galaxy.
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In general, many nuclear star clusters coexist with supermassive black holes, which are found in more than 70% of galaxies with masses greater than 100 million to 10 billion solar masses.
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“In previous work, we hypothesized that these particular stars in the middle of the Milky Way may be unusually young,” said Lund University astronomer Rebecca Forsberg.
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“Now we can confirm this. Our study shows that three of these stars are relatively young, at least as far as astronomers are concerned, ranging in age from 100 million years to about 1 billion years. We were able to determine the age.”
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“This is equivalent to the age of the Sun, which is 4.6 billion years old.”
This panorama shows the central region of the Milky Way galaxy. It builds on previous surveys by NASA’s Chandra X-ray Observatory and other telescopes, and extends Chandra’s high-energy field of view further up and down the galactic plane than previous imaging campaigns. The X-rays from Chandra are orange, green, and violet, indicating different X-ray energies. Radio data from MeerKAT is gray. Image credits: NASA / CXC / UMass / QD Wang / NRF / SARAO / MeerKAT.
In this study, Dr. Forsberg and colleagues used high-resolution data from the Keck II telescope in Hawaii. This Keck II telescope is one of the largest telescopes in the world with a 10 meter diameter mirror.
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For further verification, they measured the amount of iron, a heavy element, in the stars
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This element is important in tracking the development of galaxies. This is because astronomers’ theories about star formation and galaxy development show that the formation of heavy elements increases over time in the Universe, so younger stars contain more heavy elements.
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To determine iron levels, astronomers looked at the star’s spectrum in infrared light. Infrared light is a part of the light spectrum that can more easily illuminate dust-dense parts of the Milky Way compared to optical light.
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Researchers say there is considerable variation in iron levels.
“The very wide spread in iron levels could indicate that the innermost parts of the galaxy are incredibly heterogeneous, or unmixed,” said Dr. Brian Thorsbro, an astronomer at Lund University. Stated.
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“This is something we didn’t expect, and it tells us something not only about what the center of a galaxy looks like, but also about what the early universe looked like.”
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“Personally, I think it’s very exciting that we can now study the galactic center itself at such a detailed level,” Dr. Forsberg said.
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“While these types of measurements have been standard for observations of our own galactic disk, they have been an unattainable goal in more remote and exotic parts of the galaxy.”
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“Studies like this can teach us a lot about how our home galaxy formed and developed.”
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B. Thorsbro other. 2023. The range of old metallicities of stars in nuclear clusters is wide. APJL 958, L18; doi: 10.3847/2041-8213/ad08b1
Source: www.sci.news
