相关论文: Extremely metal-poor stars: the need for UV spectr…
The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allow us to study the formation and evolution of the elements…
We simulate a plausible cosmological model in considerable physical and numerical detail through the successive phases of reheating (at 10<z<20), formation of Pop III stars at z=15 (due to molecular hydrogen cooling), with subsequent…
The stellar metallicity is a direct measure of the amount of metals present in a galaxy, as a large part of the metals lie in its stars. In this paper we investigate new stellar metallicity indicators suitable for high-z galaxies studying…
We model early star forming regions and their chemical enrichment by Population III (Pop III) supernovae with nucleosynthetic yields featuring high [C/Fe] ratios and pair-instability supernova (PISN) signatures. We aim to test how well…
The first stars were likely more massive than those forming today and thus rapidly evolved, exploding as supernovae and enriching the surrounding gas with their chemical products. In the Local Group, the chemical signature of the first…
Elliptical galaxies probably host the most metal rich stellar populations in the Universe. The processes leading to both the formation and the evolution of such stars are discussed by means of a new multi-zone photo-chemical evolution…
We explore the predictions of the standard hierarchical clustering scenario of galaxy formation, regarding the numbers and metallicities of PopIII stars likely to be found within our Galaxy today. By PopIII we shall be referring to stars…
Thanks to the long-term collaborations between nuclear and astrophysics, we have good understanding on stellar nucleosynthesis, except for the elements around Ti and some neutron-capture elements. From the comparison between observations…
Numerical simulations have now shown that Population III (Pop III) stars can form in binaries and small clusters and that these stars can be in close proximity to each other. If so, they could be subject to binary interactions such as mass…
The element abundance ratios of four low-mass stars with extremely low metallicities indicate that the gas out of which the stars formed was enriched in each case by at most a few, and potentially only one low-energy, supernova. Such…
While the modern stellar IMF shows a rapid decline with increasing mass, theoretical investigations suggest that very massive stars (>100 solar masses) may have been abundant in the early universe. Other calculations also indicate that,…
The character of the first galaxies at redshifts z > 10 strongly depends on their level of pre-enrichment, which is in turn determined by the rate of primordial star formation prior to their assembly. In order for the first galaxies to…
We report abundance analyses of three extremely metal-poor stars with [Fe/H] $\lesssim -3$, using the Subaru High Dispersion Spectrograph (HDS). All are found to have sub-solar values of [Eu/Fe]. Comparison with our chemical evolution model…
We discuss the expected properties of the first stellar generations in the Universe. We find that it is possible to discern truly primordial populations from the next generation of stars by measuring the metallicity of high-z star forming…
To constrain the properties of the first stars with the chemical abundance patterns observed in metal-poor stars, one must identify any non-trivial effects that the hydrodynamics of metal dispersal can imprint on the abundances. We use…
We present a detailed chemical abundance and kinematic analysis of six extremely metal-poor ($-4.2 \leq$ [Fe/H] $\leq-$2.9) halo stars with very low neutron-capture abundances ([Sr/H] and [Ba/H]) based on high-resolution Magellan/MIKE…
We reconstruct the history of the cosmic star formation as well as the cosmic production of metals in the universe by means of detailed chemical evolution models for galaxies of different morphological types. We consider a picture of…
Much of the far-UV emission from elliptical galaxies is thought to arise from extreme horizontal branch stars and related objects. Only about 10% of the stellar population needs to evolve through this phase even in galaxies with the…
The first stars fundamentally transformed the early universe by emitting the first light and by producing the first heavy elements. These effects were predetermined by the mass distribution of the first stars, which is thought to have been…
We study the detectability of primordial metal-free stars. Cosmological enrichment is a local process that takes place over an extended redshift range. While the duration of this transition depends on several unknown factors, in all cases…