Collision-induced mass loss and mass gain on an extremely massive star : An analytical approach and a static proto-globular cluster test-case

Article Article scientifique Article Collision-induced mass loss and mass gain on an extremely massive star : An analytical approach and a static proto-globular cluster test-case eng 2025-06-13 author Ramirez Galeano Laura 0000-0001-8329-315X 961761 Département d'astronomie (ASTRO) author Charbonnel Corinne 22674 Département d'astronomie (ASTRO) author Fragkos Anastasios 0000-0003-1474-1523 826418 Département d'astronomie (ASTRO) author Tazakkati Zoubair 414868 author Roman Garza Jaime 924344 Département d'astronomie (ASTRO) author Gieles Mark 10.1051/0004-6361/202453462 0004-6361 https://www.aanda.org/10.1051/0004-6361/202453462 <p>The objective of this study is to analytically explore mass loss and gain induced by stellar collisions on a gas-accreting extremely massive star (aEMS, $ 10^3 ⊙ 10^4 $). We also consider its contribution to the mass budget in the context of forming multiple stellar populations (MPs) in a typical protoglobular cluster (GC). We used MESA to build a series of aEMS models up to $2 ⊙ $ for three Fe/H values, covering the metallicity range of Galactic GCs, with different treatments of super-adiabatic convection. We set analytical prescriptions to quantify collision-induced mass loss when a star spirals and deposits energy into the envelope of the aEMS. We used a Monte Carlo approach to simulate the effects of multiple collisions on an aEMS of initial mass of $10^3 M_ ⊙ $ in a static proto-GC, accounting for mass loss and gain from collisions, gas accretion, and stellar winds. We show that assumptions on super-adiabaticity in radiation-dominated layers significantly impact the aEMSs properties and their collision responses: extended stars tend to lose mass, while compact ones are more likely to gain it. Our MC simulations predict the total mass lost and gained, along with the corresponding timescales and contributions from stellar winds and collisions. The results are influenced by the structural characteristics of the aEMS and by the gas accretion rate during the collision phase. Under certain conditions, the EMS exhibits a "conveyor belt" behavior, processing up to $10^ M_ ⊙ $ of material in ∼ 5 Myrs. This study provides theoretical predictions supporting aEMSs as contributors to the abundance anomalies observed in GCs. It emphasizes the importance of including collision dynamics and mass transfer in aEMS formation and evolution models in dense stellar environments. We provide a grid of predictions for stellar M-R- Fe/H -structure relations and collision-induced mass loss and gain, suitable for inclusion in hydro and N-body simulations of star clusters.</p> Dewey 520 AGAUR SGR-2021-01069 State Agency for Research of the Spanish Ministry of Science and Innovation MCIN/AEI/10.13039/501100011033 Swiss National Science Foundation GW-Learn: Deciphering the Gravitation-Wave Universe using the Next-Generation Observatories and Machine Learning 213497 CH Programmes Swiss National Science Foundation A New Vision on Globular Cluster Archeology 192039 CH Projects 26 Département d'astronomie 12 false 866 Direction de recherche "Physique stellaire" Astronomy & astrophysics 4773d59d-2e29-4b08-90be-cfeffd1c8100 Article (Accepted version) Restricted Article_scientifique_from_crossref.pdf 5281205 application/pdf ab849095a41b1292512d339c370875a200c480d10e8904dfda77ad9fb13286a5 restrictedAccess Faculté des sciences / Département d'astronomie

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Collision-induced mass loss and mass gain on an extremely massive star : An analytical approach and a static proto-globular cluster test-case	Astronomy & astrophysics			2025	26	0

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Tazakkati, Zoubair