The strange, secluded lives of young stars at the center of the Milky Way


The strange, secluded lives of young stars at the center of the Milky Way

Search for a chart of stars included in the periodic search. The outer four-point OSIRIS gradient pattern of the GCOI was overlaid on a 2.2 μm Keck NIRC2 adaptive optic for the galactic center. Most of the specimen is located in the central gradient-signaling pattern (blue circles: early-type, orange squares: late-type). The central square is covered by all frequency points, which means that more spectra are taken from these stars throughout the night. We include all stars brighter than K = 16 mag, except for Wolf-Rayet stars (green diamond), stars that lack absorption lines (red triangle), or stars that are mistaken for other stellar sources or gas features (purple triangle). . credit: Astrophysical Journal (2023). DOI: 10.3847/1538-4357/acc93e

A new study finds that stars that live near the supermassive black hole at the center of the Milky Way galaxy have no stellar companions.

Using the W.M. Keck Observatory on Maunakea, Island of Hawaii, Devin Chu of Hilo, an astronomer with the UCLA Galactic Center Orbits Initiative, led a 10-year survey that found these “S-stars,” with the “S” standing for Sagittarius A*, the hole’s name. The monster lions at the heart of our galaxy, all on their own.

The result was surprising given that the team of S-stars Chu observed included massive young main-sequence stars only about six million years old. Typically, stars of this age, whose mass is ten times greater than our Sun, spend their childhood years with twins in binary systemor even triplets sometimes.

said Zhu, lead author of the study published in today’s issue of Astrophysical Journal. It is likely caused by the strong impact of a supermassive black hole binary star systems It either merges or crashes, where a Companion star They are expelled from the area. This may explain why we don’t see any stars with partners so close to Sagittarius A*. ”

The decade-long survey represents the first systematic investigation of binary systems within an S-star cluster.

Using the Keck Observatory’s adaptive optics system coupled to the OH-Suppressor Infrared Imaging Spectroradiometer (OSIRIS) instrument, Chu and his team tracked the motions of 28 S stars. 16 of them are young B-type stars in the main sequence and the rest are stars Low-mass, old M-type and K-type giants.

“The adaptive optics of Keck and OSIRIS were critical in providing us with the infrared insight we need to look through the dust of the galactic center as well as distinguish between individual S stars in this very crowded region,” said Chu.

Not only did they find S stars flying singly, but the researchers were also able to calculate the maximum number of S stars that could exist as binaries, a measure known as the binary fraction. They discovered that the small binary S-star fraction limit is 47 percent, which means that for every 100 S-stars, a maximum of 47 of them can be in binary systems. This limit is dramatically lower than what would be expected for similar types of young stars in Earth’s solar neighborhood, which have a binary fraction of 70 percent.

The results indicate that stars with companions have a hard time staying together in the Milky Way’s harsh environment Giant black hole.

The discovery adds to the already strange nature of S stars, whose births remain a mystery. Black hole tidal forces usually disrupt traditional star formation, raising questions about how Sagittarius A* stars managed to evolve inside the dangerous cosmic whirlpool.

“I am so grateful for the opportunity to study these strange and wonderful things stars Zhou said from my home island. “Some of the data used in this survey was taken when I was a student at Hilo Middle and High School! It is incredibly rewarding to be able to do groundbreaking science while back home in Hawaii.”

more information:
Devin S. Chu et al, Evidence for a reduced binary fraction of massive stars within 20 mparsecs of the supermassive black hole at the galactic centre, Astrophysical Journal (2023). DOI: 10.3847/1538-4357/acc93e

Introduction of
W.M. Keck Observatory

the quote: Strange, Solitary Lives of Young Stars at the Center of the Milky Way (2023, May 11) Retrieved May 13, 2023 from

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