Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei
Persistent URL
Author(s)
Gibson, Charles F. A.
Kiroglu, Fulya
Lombardi Jr., James C.
Rose, Sanaea C.
Vanderzyden, Hans D.
Mockler, Brenna
Gallegos-Garcia, Monica
Kremer, Kyle
Ramirez-Ruiz, Enrico
Rasio, Frederic A.
Date Issued
February 6, 2025
Abstract
Tidal disruption events (TDEs) are an important way to probe the properties of stellar populations surrounding supermassive black holes. The observed spectra of several TDEs, such as ASASSN-14li, show high nitrogen-to-carbon (N/C) abundance ratios, leading to questions about their progenitors. Disrupting an intermediate- or high-mass star that has undergone CNO processing, increasing the nitrogen in its core, could lead to an enhanced nitrogen TDE. Galactic nuclei present a conducive environment for high-velocity stellar collisions that can lead to high mass loss, stripping the carbon- and hydrogen-rich envelopes of the stars and leaving behind the enhanced nitrogen cores. TDEs of these stripped stars may therefore exhibit even more extreme nitrogen enhancement. Using the smoothed particle hydrodynamics code StarSmasher, we provide a parameter space study of high-velocity stellar collisions involving intermediate-mass stars, analyzing the composition of the collision products. We conclude that high-velocity stellar collisions can form products that have abundance ratios similar to those observed in the motivating TDEs. Furthermore, we show that stars which have not experienced high CNO processing can yield low-mass collision products that retain even higher N/C abundance ratios. We analytically estimate the mass fallback for a typical TDE of several collision products to demonstrate consistency between our models and TDE observations. Lastly, we discuss how the extended collision products, with high central to average density ratios, can be related to repeated partial TDEs like ASASSN-14ko and G objects in the Galactic center.
Journal
Astrophysical Journal
Department
Physics
Citation
Charles F. A. Gibson et al 2025 ApJ 980 109
Publisher
IOP Publishing Ltd
Version of Article
Published version
DOI
10.3847/1538-4357/ad9b80
ISSN
0004-637X
1538-4357
Rights
© 2025. The Author(s). Published by the American Astronomical Society.
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