Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei
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. Disru...
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/ad9b80 |
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| author | Charles F. A. Gibson Fulya Kiroğlu James C. Lombardi Jr. Sanaea C. Rose Hans D. Vanderzyden Brenna Mockler Monica Gallegos-Garcia Kyle Kremer Enrico Ramirez-Ruiz Frederic A. Rasio |
| author_facet | Charles F. A. Gibson Fulya Kiroğlu James C. Lombardi Jr. Sanaea C. Rose Hans D. Vanderzyden Brenna Mockler Monica Gallegos-Garcia Kyle Kremer Enrico Ramirez-Ruiz Frederic A. Rasio |
| author_sort | Charles F. A. Gibson |
| collection | DOAJ |
| description | 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. |
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| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-b2dcd9f996fe45c8bfd47d58cca000e92025-02-06T11:41:40ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01980110910.3847/1538-4357/ad9b80Formation of Stripped Stars from Stellar Collisions in Galactic NucleiCharles F. A. Gibson0Fulya Kiroğlu1https://orcid.org/0000-0003-4412-2176James C. Lombardi Jr.2https://orcid.org/0000-0002-7444-7599Sanaea C. Rose3https://orcid.org/0000-0003-0984-4456Hans D. Vanderzyden4https://orcid.org/0009-0009-6575-2207Brenna Mockler5https://orcid.org/0000-0001-6350-8168Monica Gallegos-Garcia6https://orcid.org/0000-0003-0648-2402Kyle Kremer7https://orcid.org/0000-0002-4086-3180Enrico Ramirez-Ruiz8https://orcid.org/0000-0003-2558-3102Frederic A. Rasio9https://orcid.org/0000-0002-7132-418XDepartment of Physics, Allegheny College , Meadville, PA 16335, USA ; gibson01@allegheny.eduCenter for Interdisciplinary Exploration & Research in Astrophysics (CIERA) and Department of Physics & Astronomy, Northwestern University , Evanston, IL 60208, USADepartment of Physics, Allegheny College , Meadville, PA 16335, USA ; gibson01@allegheny.eduCenter for Interdisciplinary Exploration & Research in Astrophysics (CIERA) and Department of Physics & Astronomy, Northwestern University , Evanston, IL 60208, USADepartment of Physics, Allegheny College , Meadville, PA 16335, USA ; gibson01@allegheny.eduThe Observatories of the Carnegie Institution for Science , Pasadena, CA 91101, USACenter for Interdisciplinary Exploration & Research in Astrophysics (CIERA) and Department of Physics & Astronomy, Northwestern University , Evanston, IL 60208, USADepartment of Astronomy & Astrophysics, University of California, San Diego, La Jolla, CA 92093, USADepartment of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, Santa Cruz , 1156 High Street, Santa Cruz, CA 95064, USACenter for Interdisciplinary Exploration & Research in Astrophysics (CIERA) and Department of Physics & Astronomy, Northwestern University , Evanston, IL 60208, USATidal 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.https://doi.org/10.3847/1538-4357/ad9b80Tidal disruptionHydrodynamical simulationsGalactic centerSupermassive black holesTransient sourcesAstrophysical black holes |
| spellingShingle | Charles F. A. Gibson Fulya Kiroğlu James C. Lombardi Jr. Sanaea C. Rose Hans D. Vanderzyden Brenna Mockler Monica Gallegos-Garcia Kyle Kremer Enrico Ramirez-Ruiz Frederic A. Rasio Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei The Astrophysical Journal Tidal disruption Hydrodynamical simulations Galactic center Supermassive black holes Transient sources Astrophysical black holes |
| title | Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei |
| title_full | Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei |
| title_fullStr | Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei |
| title_full_unstemmed | Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei |
| title_short | Formation of Stripped Stars from Stellar Collisions in Galactic Nuclei |
| title_sort | formation of stripped stars from stellar collisions in galactic nuclei |
| topic | Tidal disruption Hydrodynamical simulations Galactic center Supermassive black holes Transient sources Astrophysical black holes |
| url | https://doi.org/10.3847/1538-4357/ad9b80 |
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