相关论文: Metallicity effects in the spectral classification…

Deriving the metallicity, [Fe/H], in low-resolution spectra of carbon-enhanced metal-poor (CEMP) stars is a tedious task that, owing to the large number of line blends, often leads to uncertainties on [Fe/H] exceeding 0.25dex. The CEMP…

We present evidence that there is an M dwarf problem similar to the previously identified G dwarf and K dwarf problems: the number of low-metallicity M dwarfs is not sufficient to match simple closed-box models of local Galactic chemical…

The scaling of the specific Type Ia supernova (SN Ia) rate with host galaxy stellar mass $\dot{N}_\text{Ia} / M_\star \sim M_\star^{-0.3}$ as measured in ASAS-SN and DES strongly suggests that the number of SNe Ia produced by a stellar…

A possible relation between the high dispersion in metallicity of metal-poor halo stars and the minor merger processes in the history of the Galaxy is presented. The foreign populations of stars in the satellites through minor merger…

Metal poor dwarf galaxies in the local universe, such as those found in the RESOLVE galaxy survey, often produce high [O III]/H\b{eta} ratios close to the star forming demarcation lines of the diagnostic BPT diagram. Modeling the emission…

We use nearby K dwarf stars to measure the helium-to-metal enrichment ratio, a diagnostic of the chemical history of the Solar Neighbourhood. Our sample of K dwarfs has homogeneously determined effective temperatures, bolometric…

It is shown that the low metallicity tail of the stellar metallicity distribution predicted by simple Outflow models for the Milky Way halo depends sensitively on whether Instantaneous Recycling is adopted or relaxed. In both cases, current…

We investigate the metallicity dependence of HI surface densities in star-forming regions along many lines of sight within 70 nearby galaxies, probing kpc to 50 pc scales. We employ HI, SFR, stellar mass, and metallicity (gradient)…

Context. The study of old, metal-poor stars deepens our knowledge on the early stages of the universe. In particular, the study of these stars gives us a valuable insight into the masses of the first massive stars and their emission of…

We present the first results from MMT and Keck spectroscopy for a large sample of $0.1\leq z\leq1$ emission-line galaxies selected from our narrow-band imaging in the Subaru Deep Field. We measured the weak [OIII]$\lambda$4363 emission line…

We calculate multicomponent line-driven wind models of stars at extremely low metallicity suitable for massive first generation stars. For most of the models we find that the multicomponent wind nature is not important for either wind…

The estimate of stellar metallicities (Z*) of high-z galaxies are of paramount importance in order to understand the complexity of dust effects and the reciprocal interrelations among stellar mass, dust attenuation, stellar age, and…

Context. For stellar evolution models we rely on mass-loss rate prescriptions that show features that lack empirical confirmation, such as the bi-stability jump. This jump is an increase in mass loss in the decreasing temperature regime…

In this paper we review the observational data for OB stars in the SMC concentrating on those aspects of their spectra which provide information on processes which may strongly influence their evolution, namely mass-loss, rotational mixing…

We apply the NLTE atmosphere code FASTWIND to perform a spectroscopic study of a small sample of Galactic B-supergiants from B0 to B9. By means of the resulting data and incorporating additional datasets from alternative studies, we…

To accurately measure a star's atmospheric parameters and chemical abundances, it is crucial to have high-quality spectra. Analysing the detailed chemical abundances of groups of stars can help us better understand nucleosynthesis, galactic…

Ratios of carefully selected line depths are sensitive to stellar effective temperature ($T_\mathrm{eff}$). Relations established between line-depth ratio (LDR) and $T_\mathrm{eff}$ allow one to determine $T_\mathrm{eff}$ precisely.…

Our understanding of the evolution of He4 and Li7 depends critically on the available data for these two elements at low metallicity. In particular, the degree to which there is a slope in an abundance vs metallicity regression can help…

We present new ultra-metal-poor (UMP) stars parameters with [Fe/H]<-4.0 based on line-by-line non-local thermodynamic equilibrium (NLTE) abundances using an up-to-date iron model atom with a new recipe for non-elastic hydrogen collision…

In an attempt of clarifying the [S/Fe] behavior with the run of [Fe/H] in the metal-poor regime which has been a matter of debate, an extensive non-LTE analysis of near-IR S I triplet lines (multiplet 3) at 1.046 micron was carried out for…