Massive stars and globular cluster formation

We first present chemodynamical simulations to investigate how stellar winds of massive stars influence early dynamical and chemical evolution of forming globular clusters (GCs). In our numerical models, GCs form in turbulent, high-density giant molecular clouds (GMCs), which are embedded in a massive dark matter halo at high redshifts. We show how high-density, compact stellar systems are formed from GMCs influenced both by physical processes associated with star formation and by tidal fields of their host halos. We also show that chemical pollution of GC-forming GMCs by stellar winds from massive stars can result in star-to-star abundance inhomogeneities among light elements (e.g., C, N, and O) of stars in GCs. The present model with a canonical initial mass function (IMF) also shows a C-N anticorrelation that stars with smaller [C/Fe] have larger [N/Fe] in a GC. Although these results imply that "self-pollution'' of GC-forming GMCs by stellar winds from massive stars can cause abundance inhomogeneities of GCs, the present models with different parameters and canonical IMFs cannot show N-rich stars with [N/Fe] similar to 0.8 observed in some GCs (e.g., NGC 6752). We discuss this apparent failure in the context of massive star formation preceding low-mass ones within GC-forming GMCs ("bimodal star formation scenario''). We also show that, although almost all stars (similar to 97%) show normal He abundances (Y) of similar to 0.24, some stars later formed in GMCs can have Y as high as similar to 0.3 in some models. The number fraction of He-rich stars with Y > 0.26 is, however, found to be small (similar to 10(-3)) for most models. We discuss this result in the context of the possibly large Y-values observed in a few Galactic GCs.