相关论文: Revised Stroemgren metallicity calibration for red…

We explore the metallicity distribution function (MDF) of red giant stars in Omega Centauri from a catalogue of Washington M, T_2 and DDO51 photometry covering over 1.1 deg^2 outside the cluster core. Using updated calibrations of giant…

Among stars in Galactic globular clusters the carbon abundance tends to decrease with increasing luminosity on the upper red giant branch, particularly within the lowest metallicity clusters. While such a phenomena is not predicted by…

The near-infrared behavior of the red giant branch (RGB hereafter) as a function of abundance is examined with an unprecedented large sample of 27 Galactic globular clusters with Two Micron All Sky Survey photometry. We propose a new…

We obtained spectra of red giants in 15 Small Magellanic Cloud (SMC) clusters in the region of the CaII lines with FORS2 on the Very Large Telescope (VLT). We determined the mean metallicity and radial velocity with mean errors of 0.05 dex…

NGC 2419 is a peculiar Galactic globular cluster in terms of size/luminosity, and chemical abundance anomalies. Here, we present Str\"omgren $uvby$ photometry of the cluster. Using the gravity- and metallicity-sensitive $c_1$ and $m_1$…

We present a V-I color-magnitude diagram for a region 1'-2' from the center of M32 based on Hubble Space Telescope WFPC2 images. The broad color-luminosity distribution of red giants shows that the stellar population comprises stars with a…

Extensive oxygen abundance determinations were carried out for 239 late-G/early-K giant stars of 1.5-5 M_sun by applying the spectrum-fitting technique to O I 7771-5 and [O I] 6300/6363 lines based on the high-dispersion spectra in the red…

Analysis of cluster and field star uvby data demonstrates the existence of a previously undetected discrepancy in a widely used photometric metallicity calibration for G dwarfs. The discrepancy is systematic and strongly color-dependent,…

A Monte Carlo simulation exploring uncertainties in standard stellar evolution theory on the red giant branch of metal-poor globular clusters has been conducted. Confidence limits are derived on the absolute V-band magnitude of the bump in…

New empirical calibrations of the Red Giant Branch Tip in the I,J,H and K bands based on two fundamental pillars, namely omega Centauri and 47 Tucanae, have been obtained by using a large optical and near infrared photometric database. Our…

We report new spectroscopic observations obtained with the Michigan/Magellan Fiber System of 308 red giants (RGs) located in two fields near the photometric center of the bar of the Large Magellanic Cloud. This sample consists of 131 stars…

We present updated stellar population models appropriate for old ages (>1 Gyr) and covering a wide range in metallicities (-1.5<[Fe/H]<0.3). These models predict the full spectral variation associated with individual element abundance…

The individual reddenings for B stars in two fields in the Small Magellanic Cloud (SMC) and two fields in the Large Magellanic Cloud (LMC) are determined by means of Stroemgren uvby CCD photometry. In both LMC fields we find a foreground…

We report the first results from our program to examine the metallicity distribution of the Milky Way nuclear star cluster connected to SgrA*, with the goal of inferring the star formation and enrichment history of this system, as well as…

The tip of red giant branch (TRGB) stars have attracted intensive attention in recent years because their $I$-band absolute magnitudes, $M_\rm I$, are often used for distance calibration in the Hubble constant measurements because of its…

In the search of a sample of metal-poor bright giants using Str{\"o}mgren photometry, we serendipitously found a sample of 26 young (ages younger than 1 Gyr) metal-rich giants, some of which have high rotational velocities.We determined the…

We present the abundance analysis of stars from the tip of the red giant branch (RGB) to below the RGB-bump in the globular cluster NGC 2808, based on high resolution echelle spectra. We derived abundances of Al, alpha-process elements (Si…

We aim to analyze the chemical evolution of the Small Magellanic Cloud adding 12 additional clusters to our existing sample having accurate and homogeneously derived metallicities. We are particularly interested in seeing if there is any…

Assuming that in the atmospheres of low-mass, metal-poor red giant stars, 1-D models based on LTE accurately predict the abundance of iron from Fe II, we derive a globular cluster metallicity scale based on the equivalent widths of Fe II…

The metallicity dependence of the primary indices of the uvby photometric system for cooler dwarfs (Teff ~ 6500 K to 5000K) is investigated. The data base for the analysis is composed of the overlap between a composite catalog of selected,…