相关论文: Cosmic Chemical Evolution with an Early Population…

Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We develop models which include an early burst of…

The birth and death of the first generation of stars have important implications for the thermal state and chemical properties of the intergalactic medium (IGM) in the early universe. Sometime after recombination, the neutral, chemically…

New observations from the Hubble ultra deep field suggest that the star formation rate at z>7 drops off faster than previously thought. Using a newly determined star formation rate for the normal mode of Population II/I stars (PopII/I),…

We exploit the recent observations of extremely metal-poor (EMP) stars in the Galactic halo and investigate the constraints on the IMF of the stellar population that left these low-mass survivors of [Fe/H]<-2.5 and the chemical evolution…

I present a new Galactic chemical evolution model motivated by and grounded in the hierarchical theory of galaxy formation, as expressed by a halo merger history of the Galaxy. This model accurately reproduces the "metallicity distribution…

Motivated by the recent detection of metals in different components of the high redshift universe and by the abundance ratios measured in the extremely metal-poor stars of our Galaxy, we study the nucleosynthesis constraints that this…

The cosmic star formation histories are evaluated for different minimum masses of the initial halo structures, with allowance for realistic gas outflows. With a minimum halo mass of 10^{7} - 10^{8} M_odot and a moderate outflow efficiency,…

The first stars hold intrinsic interest for their uniqueness and for their potential importance to galaxy formation, chemical enrichment, and feedback on the intergalactic medium (IGM). The metal-free composition of the first stars…

We use the growing data sets of very-metal-poor stars to study the impact of stellar winds of fast rotating massive stars on the chemical enrichment of the early Galaxy. We use an inhomogeneous chemical evolution model for the Galactic halo…

The first stars fundamentally transformed the early Universe through their production of energetic radiation and the first heavy chemical elements. The impact on cosmic evolution sensitively depends on their initial mass function (IMF),…

A few topics concerning the early chemical evolution of the Milky Way are critically discussed. In particular, it is argued that: 1) Observed abundance patterns of extremely metal poor stars (of Pop. II) do not constrain the mass range of…

The early chemical evolution of the Galaxy and the Universe is vital to our understanding of a host of astrophysical phenomena. Since the most metal-poor Galactic stars (with metallicities down to [Fe/H]\sim-5.5) are relics from the…

Nucleosynthetic signatures in common between the gas responsible for the high redshift Lyman alpha forest and a subsample of extremely metal poor stars are found. A simple mass loss model of chemical evolution with physically motivated…

A model for Galactic chemical evolution, driven by supernova-induced star formation, is formulated and used to examine the nature of the Galactic halo at early epochs. In this model, new stars are formed following each supernova event, thus…

We propose a semi-analytic model that is developed to understand the cosmological evolution of the mean metallicity in the Universe. In particular, we study the contributions of Population III (Pop III) and Population II (Pop II) stars to…

The chemical enrichment of the early Universe is a crucial element in the formation and evolution of galaxies, and Population III (PopIII) stars must play a vital role in this process. In this study, we examine metal enrichment from massive…

The first stars are assumed to be predominantly massive. Although, due to the low initial abundances of heavy elements the line-driven stellar winds are supposed to be inefficient in the first stars, these stars may loose a significant…

We calculate the evolution of zero-metallicity Population III (Pop III) stars whose mass grows from the initial mass of $\sim 1M_{\odot}$ by accreting the surrounding gases. Our calculations cover a whole evolutionary stages from the…

We studied the effects of a hypothetical initial stellar generation (PopIII) of only massive and very massive stars (VMS) on the chemical evolution of the Galaxy. We adopted the two-infall chemical evolution model of Chiappini et al. and…

We investigate the intrinsic scatter in the chemical abundances of a sample of metal-poor ([Fe/H]<-2.5) Milky Way halo stars. We draw our sample from four historic surveys and focus our attention on the stellar Mg, Ca, Ni, and Fe…