Evolution of stars with 60 and 200 M⊙: predictions for WNh stars in the Milky Way

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00619117" target="_blank" >RIV/67985815:_____/25:00619117 - isvavai.cz</a>

Výsledek na webu

<a href="https://hdl.handle.net/11104/0365890" target="_blank" >https://hdl.handle.net/11104/0365890</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202451565" target="_blank" >10.1051/0004-6361/202451565</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Evolution of stars with 60 and 200 M⊙: predictions for WNh stars in the Milky Way

Popis výsledku v původním jazyce

Massive stars are characterised by powerful stellar winds driven by radiation, thus, the mass-loss rate is known to play a crucial role in their evolution. Aims. We study the evolution of two massive stars (a classical massive star and a very massive star) at solar metallicity (Z = 0.014) in detail. We calculate their final masses, radial expansion, and chemical enrichment, at their H-core, He-core, and C-core burning stages, prior to their final collapse. Methods. We ran evolutionary models for initial masses of 60 and 200 M-circle dot using MESA and the Geneva-evolution-code (GENEC). For the mass loss, we adopted the self-consistent m-CAK prescription for the optically thin winds of OB-type stars, a semi-empirical formula for H-rich optically thick wind of luminous Wolf-Rayet (WR) stars of the nitrogen sequence with hydrogen in their spectra (WNh stars), and a hydrodynamically consistent formula for the H-poor thick wind of classical WR stars. The transition from thin to thick winds was set to Gamma(e) = 0.5. Results. The unification of the initial set-up for the stellar structure and wind prescription leads to very similar black hole mass for both GENEC and MESA codes, but both codes predict different tracks across the Hertzsprung-Russell diagram (HRD) For the 60 M-circle dot case, the GENEC model predicts a more efficient rotational mixing and more chemically homogeneous evolution, whereas the MESA model predicts a large radial expansion that reaches the Luminous Blue Variable (LBV) phase. For the 200 M-circle dot case, differences between both evolution codes are less relevant because their evolution is dominated by wind mass loss with a weaker dependence on internal mixing. Conclusions. The switch of the mass-loss prescription based on the Eddington factor instead of the removal of outer layers, implies the existence of WNh stars with a large mass fraction of hydrogen at the surface (X-surf >= 0.3) formed from initial masses of greater than or similar to 60 M-circle dot. These stars are constrained in a T-eff range of the HRD which corresponds to the main sequence band, in agreement with the observations of Galactic WNh stars at Z = 0.014. While our models employ a fixed Gamma(e, trans) threshold for the switch to thick winds, rather than a continuous thin-to-thick wind model, the good reproduction of observations during the main sequence supports the robustness of the wind model upgrades, allowing its application to studies of late-stage stellar evolution before core collapse.

Název v anglickém jazyce

Evolution of stars with 60 and 200 M⊙: predictions for WNh stars in the Milky Way

Popis výsledku anglicky

Massive stars are characterised by powerful stellar winds driven by radiation, thus, the mass-loss rate is known to play a crucial role in their evolution. Aims. We study the evolution of two massive stars (a classical massive star and a very massive star) at solar metallicity (Z = 0.014) in detail. We calculate their final masses, radial expansion, and chemical enrichment, at their H-core, He-core, and C-core burning stages, prior to their final collapse. Methods. We ran evolutionary models for initial masses of 60 and 200 M-circle dot using MESA and the Geneva-evolution-code (GENEC). For the mass loss, we adopted the self-consistent m-CAK prescription for the optically thin winds of OB-type stars, a semi-empirical formula for H-rich optically thick wind of luminous Wolf-Rayet (WR) stars of the nitrogen sequence with hydrogen in their spectra (WNh stars), and a hydrodynamically consistent formula for the H-poor thick wind of classical WR stars. The transition from thin to thick winds was set to Gamma(e) = 0.5. Results. The unification of the initial set-up for the stellar structure and wind prescription leads to very similar black hole mass for both GENEC and MESA codes, but both codes predict different tracks across the Hertzsprung-Russell diagram (HRD) For the 60 M-circle dot case, the GENEC model predicts a more efficient rotational mixing and more chemically homogeneous evolution, whereas the MESA model predicts a large radial expansion that reaches the Luminous Blue Variable (LBV) phase. For the 200 M-circle dot case, differences between both evolution codes are less relevant because their evolution is dominated by wind mass loss with a weaker dependence on internal mixing. Conclusions. The switch of the mass-loss prescription based on the Eddington factor instead of the removal of outer layers, implies the existence of WNh stars with a large mass fraction of hydrogen at the surface (X-surf >= 0.3) formed from initial masses of greater than or similar to 60 M-circle dot. These stars are constrained in a T-eff range of the HRD which corresponds to the main sequence band, in agreement with the observations of Galactic WNh stars at Z = 0.014. While our models employ a fixed Gamma(e, trans) threshold for the switch to thick winds, rather than a continuous thin-to-thick wind model, the good reproduction of observations during the main sequence supports the robustness of the wind model upgrades, allowing its application to studies of late-stage stellar evolution before core collapse.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Svazek periodika

696

Číslo periodika v rámci svazku

Apr.

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

15

Strana od-do

A72

Kód UT WoS článku

001459780300006

EID výsledku v databázi Scopus

2-s2.0-105007618833