High power accretion in massive binary systems and the impact of metallicity

During a giant eruption of a very massive star in the binary system, the companion star can accrete a large amount of mass that can change its properties and potentially its subsequent evolution. The effect depends on the companion mass, metallicity, the amount of mass it accreted, orbital parameters and other parameters. We simulate individual companion stars assuming they undergo such accretion events. We study the envelope properties of 20 M ⊙ and 30 M ⊙ single massive stars at different metallicities ( Z = 0 . 02 , Z = 0 . 008 and Z = 0 . 004 ) during accretion at different rates, from 1 0 − 5 to 1 0 − 2 M ⊙ yr − 1 . For the lower accretion rates we simulate, the stars remains hot, while at higher accretion rates, it becomes cooler and inflates. This behavior is observed in both stars but occurs at different accretion rates. Higher metallicity stars exhibit greater variations in accretion luminosity for the same accretion rate and stellar mass compared to lower metallicity stars. While higher metallicity stars typically have larger stellar envelopes, suggesting smaller variations in luminosity at Galactic metallicity compared to the LMC and SMC, our results show the opposite. • Companions may accrete mass during giant eruptions of massive stars. • Accretion alters stellar properties and may affect long-term evolution. • Effects depend on mass, metallicity, accreted mass, and orbital factors. • We model 20 M ⊙ and 30 M ⊙ stars at Z=0.02, 0.008, and 0.004 with MESA. • Low accretion keeps stars hot; high accretion causes cooling and inflation. • High-Z stars show larger luminosity variation than low-Z stars at same rate.