The team found that there are surprisingly many very young stars in IRS13. “It seems that the IRS13 star cluster is the key to revealing the origin of the nuclear star cluster, i.e. the densest grouping of stars in our Galaxy,” Zajaček told Právu.
The star cluster is located in the immediate vicinity of the supermassive black hole Sgr A* at the center of our Galaxy. It was discovered 20 years ago, but only now has it been possible to determine the character of the individual stars in the star cluster.
A large number of young stars
However, everything is not as it should be, that is, to be more precise, as scientists assumed. The stars in it should be significantly older.
“In reality, it shouldn’t be possible for such a large number of young stars to exist in the immediate vicinity of a supermassive black hole,” explained the astrophysicist. Young stars include, for example, X3 from this group. The interesting thing is that there are stars of different ages in the cluster, while some of them are still forming.
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The analysis of the IRS13 cluster is the first attempt to solve the decade-old mystery of the unexpected young stars at the center of the Galaxy. In addition to IRS13, there is a star cluster S next to it, even closer to the black hole.
Astronomer Andrea M. Ghezová from the University of California found that the members of the S-cluster are significantly younger than would correspond to theories of star formation. She won the 2020 Nobel Prize for this very unconventional discovery.
Wild Past IRS13
In addition to the current unexpected discovery of young stars as well as water ice in the IRS13 star cluster using the James Webb Space Telescope, scientists also discovered that IRS13 appears to have had a turbulent formation history. This may be the answer to the question of why it has so many young stars.
It is likely that IRS13 traveled towards the supermassive black hole through dynamical friction with its surroundings, literally bumping into other star clusters in the process.
As IRS13 plunged deeper into the Galaxy, it was then “captured” by the black hole’s gravity. During this process, a dense shock wave may have formed in front of the falling star cluster, similar to the wave that forms in the water at the bow of a ship. This could have created the conditions for star formation. This is at least one of the explanations why these young stars are mostly located in front of the star cluster, added Zajaček.
Foto: Astrophysical Journal
K- and L-band infrared image of the inner region of our galactic center taken with the infrared camera (NACO detector) on the Very Large Telescope (VLT) at the European Southern Observatory, Chile. The cluster IRS13 is marked in green. The four squares indicate the pointing areas for spectroscopic observations by the James Webb Space Telescope.
Foto: Astrophysical Journal
An infrared spectrum obtained with the James Webb Space Telescope (NIRSpec) at wavelengths between 1.5 and 3.2 micrometers. The spectrum shows prominent emission lines belonging to ionized hydrogen and helium. Absorption bands belonging to the CO molecule and water ice reveal cooler material surrounded by dominantly ionized material.
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2023-10-13 12:34:28
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