A Study of Wolf-Rayet stars Formed via Chemically Homogeneous Evolution

Understand

Using the stellar evolution code---Modules for Experiments in Stellar Astrophysics (MESA), we investigate the evolution of massive stars with different rotational velocities and metallicities towards Wolf-Rayet stars.

• In our simulations, the initial rotating velocities are taken as 0, 250, 500 and 650 km s$^{-1}$, and the metallicities equal to 0.02, 0.014, 0.008, 0.006, 0.004 and 0.002.
• We show our rapid rotation models in the HR diagram compared with the observations.
• We find that the rotational mixing is less efficient at high metallicity, and these stars become Wolf-Rayet (WR) stars when the helium in their center is ignited.