Related papers: Luminosity-metallicity relation for stars on the l…
A most desirable feature of a standard candle to estimate astronomical distances is robustness against changes in metallicity and age. It is argued that the radii of main sequence stars with spectral types from solar to A0 show predictable…
Context. Several new techniques to determine the metallicity of M dwarfs with better precision have been developed over the last decades. However, most of these studies were based on empirical methods. In order to enable detailed abundance…
88 dwarfs, covering the colour index interval 0.37 <(B-V)o <= 1.07 mag, with metallicities -2.70 <= [Fe/H] <= +0.26 dex have been taken from three different sources for new metallicity calibration. The catalogue of Cayrel de Stroble et al.…
We present a study of metallicities in a sample of main sequence stars with spectral types M, K, G and F ($T_{\rm eff}$ $\sim$ 3200 -- 6500K and log $g$ $\sim$ 4.3 -- 5.0 dex) belonging to the solar neighborhood young open cluster Coma…
We briefly describe our on-going investigation of the near-IR luminosity-metallicity relationship for dwarf irregular galaxies in nearby groups of galaxies. The motivations of the project and the observational databases are introduced, and…
We present a statistical parallax study of nearly 2,000 M subdwarfs with photometry and spectroscopy from the Sloan Digital Sky Survey. Statistical parallax analysis yields the mean absolute magnitudes, mean velocities and velocity…
It is shown that bright cluster dwarf ellipticals follow a relation between metallicity and apparent flattening. Rounder dwarfs tend to be more metal-rich. The evidence is based on colour as well as spectroscopic line-strength data from the…
We present new period-luminosity and period-luminosity-metallicity relations for Galactic RR Lyrae stars based on a sample of 28 pulsators located at distances up to $1.5$ kpc from the Sun. Near-infrared photometry was obtained at the Cerro…
Aims. In this work we develop a technique to obtain high precision determinations of both metallicity and effective temperature of M dwarfs in the optical. Methods. A new method is presented that makes use of the information of 4104 lines…
We present a new approach to study the mass-metallicity relation and its dependency on time. We used the star formation history (SFH) derived from color-magnitude diagram fitting techniques of a sample of Local Group (LG) dwarfs to obtain…
Large numbers of low-to-medium resolution spectra of M-type dwarf stars from both the local Galactic disk and halo are available from various surveys. In order to fully exploit these data, we develop a template-fit method using a set of…
We present relation of the mean I-band brightness of red clump stars on metallicity. Red clump stars were proposed to be a very attractive standard candle for distance determination. The calibration is based on 284 nearby red giant stars…
We describe a method for accurately determining M dwarf metallicities with spectral synthesis based on abundance analyses of visual binary stars. We obtained high resolution, high signal-to-noise spectra of each component of five visual…
We present metallicities, radial velocities and near-infrared spectral types for 447 M dwarfs determined from moderate resolution (R~2000) near-infrared (NIR) spectra obtained with IRTF/SpeX. These M dwarfs are targets of the MEarth Survey,…
We present empirical metallicity-dependent calibrations of effective temperature against colours for dwarfs of luminosity classes IV and V and for giants of luminosity classes II and III, based on a collection from the literature of about…
We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way…
The relativley large spread in the derived metallicities ([Fe/H]) of M dwarfs shows that various approaches have not yet converged to consistency. The presence of strong molecular features, and incomplete line lists for the corresponding…
We present the metallicity distribution function (MDF) for 24,270 G and 16,847 K dwarfs at distances from 0.2 to 2.3 kpc from the Galactic plane, based on spectroscopy from the Sloan Extension for Galactic Understanding and Exploration…
RR Lyrae (RR Lyr) stars are a well-known and useful distance indicator for old stellar populations such as globular clusters and dwarf galaxies. Fundamental-mode RR Lyr (RRab) stars are commonly used to measure distances, and the accuracy…
The aim of the project is to define a metallicity/gravity/temperature scale vs spectral types for metal-poor M dwarfs. We obtained intermediate-resolution ultraviolet (R~3300), optical (R~5400), and near-infrared (R~3900) spectra of 43 M…