Yields of rotating stars at solar metallicity

Abstract

We present a new set of stellar yields obtained from rotating stellar models at solar metallicity covering the massive star range (12-60 solar masses). The stellar models were calculated with the latest version of the Geneva stellar evolution code described in Hirschi et al (2004). Evolution and nucleosynthesis are in general followed up to silicon burning. The yields of our non-rotating models are consistent with other calculations and differences can be understood in the light of the treatment of convection and the rate used for C12(a,g)O16. This verifies the accuracy of our calculations and gives a safe basis for studying the effects of rotation on the yields. The contributions from stellar winds and supernova explosions to the stellar yields are presented separately. We then add the two contributions to compute the total stellar yields. Below about 30 solar masses, rotation increases the total metal yields, Z, and in particular the yields of carbon and oxygen by a factor of 1.5-2.5. As a rule of thumb, the yields of a rotating 20 solar masses star are similar to the yields of a non-rotating 30 solar masses star, at least for the light elements considered in this work. For very massive stars (around 60 solar masses), rotation increases the yield of helium but does not significantly affect the yields of heavy elements.