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

摘要: Massive rotating single stars with an initial metal composition appropriate for the dwarf galaxy I Zw 18 ([Fe/H]=$-$1.7) are modelled during hydrogen burning masses of 9-300 M$_{\odot}$ and rotational velocities 0-900 km s$^{-1}$. Internal mixing processes in these models were calibrated based on observed sample OB-type Magellanic Clouds. Even moderately fast rotators, which may be abundant at this metallicity, found to undergo efficient induced by rotation resulting quasi chemically-homogeneous evolution. These homogeneously-evolving reach effective temperatures up 90 kK core burning. This, together their moderate mass-loss rates, make them Transparent Wind Ultraviolet INtense (TWUIN star), expected numbers might explain HeII ionizing photon flux other low-metallicity galaxies. Our slowly above $\sim$80 evolve into late B- M-type supergiants burning, visual magnitudes 19$^{\mathrm{m}}$ distance 18. Both types stars, TWUIN luminous late-type supergiants, only predicted low metallicity. star evolution metallicity is shown differ qualitatively from that metal-rich environments. grid can used interpret observations local star-forming galaxies high-redshift galaxies, as well metal-poor components our Milky Way its globular clusters.