Two populations of metal-free stars in the early Universe

摘要: We construct star formation histories at redshifts z? 5 for two physically distinct populations of primordial, metal-free stars, motivated by theoretical and observational arguments that have hinted towards the existence an intermediate stellar generation between Population III I/II. Taking into account cosmological parameters as recently revised Wilkinson Microwave Anisotropy Probe after three years operation, we determine self-consistent reionization discuss resulting chemical enrichment from these early generations. find bulk ionizing photons heavy elements produced high must originated in II.5 which formed out primordial gas haloes with virial temperatures?10 4 K, had typical masses?10M ⊙ . Classical minihaloes having masses?100 M , on other hand, only a minor impact metal enrichment. Specifically, conclude ≃ 10 per cent mass went III.