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Stellar Collisions in the Galactic Center

Presentation #200.06 in the session Galaxy Dynamics 2: Black Holes and Dark Matter.

Published onJul 01, 2023
Stellar Collisions in the Galactic Center

Like most galaxies, the Milky Way harbors a supermassive black hole (SMBH) at its center, surrounded by a dense nuclear star cluster. Most stars within this cluster will experience at least one direct collision with another star before evolving off the main-sequence. Using a statistical approach, we characterize the outcomes of these stellar collisions within the inner parsec of the Galactic Center (GC). Close to the SMBH, where the velocity dispersion is larger than the escape speed from a Sun-like star, collisions lead to mass loss. We find that the stellar population within 0.01 pc is halved within about a Gyr because of destructive collisions. Additionally, we predict a diffuse population of peculiar low-mass stars in the GC. These stars have been divested of their outer layers in the inner 0.01 pc before migrating to larger distances from the SMBH. Between 0.01 and 0.1 pc from the SMBH, collisions can result in mergers. Our results suggest that repeated collisions between lower mass stars can produce massive (> 10 M) stars, and there may over 100 of them residing in this region. We also provide predictions on the number of G objects, dust and gas enshrouded stellar objects, that may result from main-sequence stellar collisions. Lastly, we comment on possible connections between stellar collisions and the missing red giants in the GC.

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