相关论文: Possible signature of hypernova nucleosynthesis in…

We review Galactic halo formation theories and supporting evidence, in particular kinematics and detailed chemical abundances of stars in some relevant globular clusters as well as Local Group dwarf galaxies. Outer halo red HB clusters tend…

We present chemical composition and fundamental parameters (the effective temperature, surface gravity and radius) for four sharp-lined A-type stars ${\gamma}$ Gem (HD 41705), o Peg (HD 214994), ${\theta}$ Vir (HD 114330) and ${\nu}$ Cap…

We present chemical abundances of the very bright metal-poor star HD~1936 based on high-resolution and high SNR spectra from AUKR. We obtain the abundances of 29 atomic species with atomic numbers between 3 and 63. In this context, the…

ABRIDGED: To compare the chemistries of stars in the Milky Way dSph galaxies with stars in the Galaxy, we have compiled a large sample of Galactic stellar abundances from the literature. As found in previous studies, the [alpha/Fe] ratios…

Spectra of unevolved metal-poor halo stars uniquely reflect the elemental abundances incorporated during the earliest Galactic epoch. Their heavy-element content is well understood as the products of neutron capture on iron-peak elements.…

We present Keck/HIRES observations of six metal-poor stars in two of the ultra-faint dwarf galaxies orbiting the Milky Way, Ursa Major II and Coma Berenices. These observations include the first high-resolution spectroscopic observations of…

Following the recent abundance measurements of Mg, Al, Ca, Fe, and Ni in the black hole X-ray binary XTE J1118+480 using medium-resolution Keck II/ESI spectra of the secondary star (Gonz\'alez Hern\'andez et al. 2006), we perform a detailed…

We present a chemical abundance analysis of the faint halo metal-poor main-sequence star J0023+0307, with [Fe/H]<-6.3, based on a high-resolution (R~35,000) Magellan/MIKE spectrum. The star was originally found to have [Fe/H]< -6.6 based on…

The discovery of extremely zirconium- and lead-rich surfaces amongst a small subgroup of hot subdwarfs has provoked questions pertaining to chemical peculiarity in hot star atmospheres and about their evolutionary origin. With only three…

Study of primary stars lying in Sirius-like systems with various masses of WD companions and orbital separations is one of the key aspects to understand the origin and nature of Barium (Ba) stars. In this paper, based on high resolution and…

Li abundances in the bulk of low-mass metal-poor stars are well reproduced by stellar evolution models adopting a constant initial abundance. However, a small number of stars have exceptionally high Li abundances, for which no convincing…

We report the discovery of SMSS J160540.18-144323.1, a new ultra-metal poor halo star discovered with the SkyMapper telescope. We measure [Fe/H] = -6.2 +- 0.2 (1D LTE), the lowest ever detected abundance of iron in a star. The star is…

Lithium abundances in a selected sample of halo stars have been revised by using new accurate Teff. From 41 plateau stars we found no evidence for intrinsic dispersion, a tiny trend with Teff and no trend with [Fe/H]. These results argue…

Compilations of abundances of Strontium and Barium in extremely metal-poor stars show that an apparent cutoff is observed for [Sr/Ba] at [Fe/H]$<$-3.6 and large fluctuations for [Fe/H]$>$-3.6 with a clear upper bound depending on…

The most metal-poor stars in dwarf spheroidal galaxies (dSphs) can show the nucleosynthetic patterns of one or a few supernovae. These supernovae could have zero metallicity, making metal-poor dSph stars the closest surviving links to…

Recently models based on the acceleration of metal-rich material inside superbubbles have been proposed to account for the observed abundances of Be and B in metal-poor halo stars. We analyse some of the implications of these models for the…

Based on high quality spectral data (spectral resolution R>60000) within the wavelength range of 3550-5000 AA we determined main parameters (effective temperature, surface gravity, microturbulent velocity, and chemical element abundances…

Chemical abundances of six extremely metal-poor ([Fe/H]<-2.5) stars in the Sextans dwarf spheroidal galaxy are determined based on high resolution spectroscopy (R=40,000) with the Subaru Telescope High Dispersion Spectrograph. (1) The Fe…

The formation of supermassive stars has generally been studied under the assumption of rapid accretion of pristine metal-free gas. Recently it was found, however, that gas enriched to metallicities up to $Z \sim 10^{-3}$ Z$_{\odot}$ can…

For the purpose of deriving the helium abundances in chemically peculiar stars, the importance of assuming a correct helium abundance has been investigated for determining the effective temperature and gravity of main sequence B-type stars,…