Low-metallicity massive single stars with rotation. Evolutionary models applicable to I Zwicky 18

Understand

Massive rotating single stars with an initial metal composition appropriate for the dwarf galaxy I Zw 18 ([Fe/H]=$-$1.7) are modelled during hydrogen burning for initial masses of 9-300 M$_{\odot}$ and rotational velocities of 0-900 km s$^{-1}$.

• Internal mixing processes in these models were calibrated based on an observed sample of OB-type stars in the Magellanic Clouds.
• Even moderately fast rotators, which may be abundant at this metallicity, are found to undergo efficient mixing induced by rotation resulting in quasi chemically-homogeneous evolution.
• These homogeneously-evolving models reach effective temperatures of up to 90 kK during core hydrogen burning.