Related papers: Red giant stars in NGC 5128
(abridged) We present B,V,I CCD photometry of about 40000 stars in four regions of the Fornax dSph. Using the resultant CMDs, many already known age-tracers are investigated, and new CMD features are also detected: we show that blue HB…
Understanding the age and metallicity dependence of the absolute magnitude and colour of red clump (RC) stars is crucial for validating the accuracy of stellar evolution models and enhancing their reliability as a standard candle. However,…
We present multi-wavelength observations of the northern population of Omega Cen from the main-sequence turn-off to high on the red giant branch. We show that the best information about the metallicity and age of the stars can be gained…
We review our recent studies of the globular cluster system of NGC 5128. First, we have obtained low-resolution, high signal-to-noise spectroscopy of 72 globular clusters using Gemini-S/GMOS to obtain the ages, metallicities, and the level…
We perform a detailed abundance analysis on integrated-light spectra of 20 globular clusters (GCs) in the early-type galaxy NGC 5128 (Centaurus A). The GCs were observed with X-Shooter on the VLT. The cluster sample spans a metallicity…
I present details of the variations of several hundred red giant stars on time scales of a few hours to a few days from Hubble Space Telescope (HST) observations of a low-extinction galactic bulge sample from an intensive seven day…
We present a homogeneous metallicity analysis of old stellar populations in Local Volume (LV) galaxies using data from the CMDs/TRGB catalog of the Extragalactic Distance Database (EDD; http://edd.ifa.hawaii.edu), which provides uniformly…
The Advanced Camera for Surveys (ACS) on HST has been used to image two fields in the core of the Virgo cluster that contain a number of dwarf elliptical galaxies. The combined F555W and F814W images have resolved red giant stars in these…
The M33 galaxy is a nearby, relatively metal-poor, late-type spiral. Its proximity and almost face-on inclination means that it projects over a large area on the sky, making it an ideal candidate for wide-field CCD mosaic imaging.…
We examine the biases inherent to chemical abundance distributions when targets are selected from the red giant branch (RGB), using simulated giant branches created from isochrones. We find that even when stars are chosen from the entire…
Using the theoretical stellar population synthesis models of BC96, Kong et al. (2003) showed that some BATC colors and color indices could be used to disentangle the age and metallicity effect. They found that there is a very good relation…
To investigate the asymptotic giant branch (AGB) population in the Galactic halo, we search for pulsating AGB stars at a heliocentric distance over 50kpc. Our research is based on the Catalina Southern Survey (CSS) catalogue of variables,…
Observations in the IJKs wave bands covering the central 20'x20' of the Local Group galaxy NGC 6822 have been performed from the William Herschel Telescope in La Palma. They have allowed us to characterize, for the first time in the…
We study the brightness variations of galactic red supergiant stars using long-term visual light curves collected by the American Association of Variable Star Observers (AAVSO) over the last century. The full sample contains 48 red…
We have obtained spectra for 50 candidate red giants in Andromeda II (a dwarf spheroidal companion of M31) using LRIS on the Keck II telescope. After eliminating background galaxies and Galactic foreground stars, we are left with a sample…
Known bright S stars, recognized as such by their enhanced s-process abundances and C/O ratio, are typically members of the asymptotic giant branch (AGB) or the red giant branch (RGB). Few modern digital spectra for these objects have been…
The main atmospheric parameters and abundances of the iron group elements (vanadium, chromium, iron, cobalt and nickel) are determined for 62 red giant "clump" stars revealed in the Galactic field by the Hipparcos orbiting observatory. The…
Red supergiants are a short-lived stage in the evolution of moderately massive stars (10-25Mo), and as such their location in the H-R diagram provides an exacting test of stellar evolutionary models. Since massive star evolution is strongly…
The abundance and spatial distribution of dwarf galaxies are excellent empirical benchmarks to test models of structure formation on small scales. The nearby Centaurus group, with its two subgroups centered on CenA and M83, stands out as an…
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…