Rotating massive stars: Pre-SN models and stellar yields at solar metallicity

We present a new set of stellar yields obtained from rotating stellar models at solar metallicity covering the massive star range (9-120 M-circle dot). The stellar models were calculated with the latest version of the Geneva stellar evolution code described in [1]. Evolution and nucleosynthesis are in general followed up to Silicon burning. The contributions from stellar winds and from supernova explosions to the stellar yields were calculated separately. The two contributions were then added to compute the total stellar yields [2]. The effects of rotation on pre-supernova models are significant between 15 and 30 M-circle dot. Above 20 M-circle dot, rotation may change the radius or colour of the supernova progenitors (blue instead of red supergiant) and the supernova type (IIb or Ib instead of II). Rotation increases the alpha and CO core sizes by a factor similar to 1.5. Thus, rotation increases the yields for heavy elements and in particular for carbon and oxygen by a factor 1.5-2.5. Rotating models produce larger yields for C-12 and O-16 in the mass range between 9 and about 35 M-circle dot compared to the 1992 calculations [3]. For Wolf-Rayet stars (M >= 30M(circle dot)), the pre-supernova structures are mostly affected by the intensities of the stellar winds and less by rotation [4]. In this mass range, rotation increases the yields of helium and other hydrogen burning products but does not significantly affect the yields of elements produced in more advanced evolutionary stages. Note that the final masses of the most massive stellar models (similar to 120 M-circle dot) are similar to the final masses of less massive stars (similar to 40 M-circle dot) due to the use of revised mass loss rates from Nugis and Lamers 2000 [5]. The most massive stars are therefore also expected to form black holes.