相关论文: Panchromatic calibration of Ca II triplet luminosi…

Optical emission-line ratios are traditionally used to estimate gas metallicities from observed galaxy spectra. While such estimators have been calibrated primarily at low redshift, they are commonly used to study high-redshift galaxies,…

We present a revised TRGB calibration, accurate to 2.7% of distance. A modified TRGB magnitude corrected for the color dependence of the TRGB, the QT magnitude, is introduced for better measurement of the TRGB. We determine the…

The purpose of this study is to carry out a thorough investigation of the changes in morphology of the red giant branch (RGB) of Galactic globular clusters (GGC) as a function of metallicity, in the V,I bands. To this aim, two key points…

We present an unprecedented spectroscopic survey of the CaII triplet + OI for a sample of 14 luminous ($-$26 $\gtrsim$ M$_V$ $\gtrsim$ $-$29), intermediate redshift (0.85 $\lesssim$ $z$ $\lesssim$ 1.65) quasars. The ISAAC spectrometer at…

Context. Departures from local thermodynamic equilibrium (LTE) distort the calcium abundance derived from stellar spectra in various ways, depending on the lines used and the stellar atmospheric parameters. The collection of atomic data…

Synthetic-template subtraction is widely used to measure chromospheric activity in large spectroscopic surveys. However, many solar-like FGK stars show systematically negative Ca II infrared triplet (IRT) residual indices, implying that the…

In this paper we present simulated observations of galaxies at z=2 and z=3 to probe the capabilities of next-generation telescopes (E-ELT and JWST) to measure the structural and photometrical properties of high redshift galaxies. We carry…

Stellar loci are widely used for selection of interesting outliers, reddening determinations, and calibrations. However, hitherto the dependence of stellar loci on metallicity has not been fully explored and their intrinsic widths are…

For a sample of metal-poor stars (-3.3< [Fe/H] <-2.2) that have high-resolution spectroscopic abundance determinations, we have measured equivalent widths (EW) of the Ca II K, Mg I b and near-infrared (NIR) Ca II triplet lines using…

In the fourth paper of this series, we present the metallicity-dependent Sloan Digital Sky Survey (SDSS) stellar color loci of red giant stars, using a spectroscopic sample of red giants in the SDSS Stripe 82 region. The stars span a range…

We measure the Ca II 8542 line strength in 3360 stars along three lines-of-sight in the Galactic bar: (l,b) ~ (+/-5.0,-3.5) and Baade's Window, using Fabry-Perot (FP) absorption line spectroscopy. This is the first attempt to show that…

We measure the central values (within Re/8) of the CaII triplet line indices CaT* and CaT and the Paschen index PaT at 8600 AA for a 93%-complete sample of 75 nearby early-type galaxies with BT<12 and Vgal<2490 km/s. We find that the values…

We compare our compilation of the W' calcium index for 71 Galactic globular clusters to the widely used Zinn and West (1984 ApJS, 55, 45) [Fe/H] scale and to Carretta and Gratton's (1997 A&A Supplement 121, 95) scale from high-dispersion…

The Complete Calibration of the Colour-Redshift Relation survey (C3R2) is a spectroscopic effort involving ESO and Keck facilities designed to empirically calibrate the galaxy colour-redshift relation - P(z|C) to the Euclid depth…

Despite the advances provided by large-scale photometric surveys, stellar features - such as metallicity - generally remain limited to spectroscopic observations often of bright, nearby low-extinction stars. To rectify this, we present a…

Although measuring the gas metallicity in galaxies at various redshifts is crucial to constrain galaxy evolutionary scenarios, only rest-frame optical emission lines have been generally used to measure the metallicity. This has prevented us…

Knowledge of stellar atmospheric parameters ($T_{\rm eff}$, $\log{g}$, [Fe/H]) of M dwarfs can be used to constrain both theoretical stellar models and Galactic chemical evolutionary models, and guide exoplanet searches, but their…

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 high quality near infrared Color Magnitude Diagrams of 10 Galactic Globular Clusters (GCs) spanning a wide metallicity range (-2.15<[Fe/H]<-0.2). This homogeneous data-base has been used to perform a detailed analysis of the Red…

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.…