Related papers: SALT and RR Lyrae variables: Our Galaxy, The Magel…
Data of our compiled catalog containing the positions, velocities, and metallicities of 415 RR~Lyrae variable stars and the relative abundances [el/Fe] of 12~elements for 101 RR~Lyrae stars, including four $\alpha$~elements (Mg, Ca, Si, and…
We report the discovery of a large number of short-period variable stars in the dwarf irregular galaxy NGC6822, based on deep time-series imaging carried out with the ESO Very Large Telescope. In particular, we found a modest population of…
The structure and kinematics of the old component of the Galactic bulge are still a matter of debate. The bulk of the bulge as traced by red clump stars includes two main components, which are usually identified as the metal-rich and…
The Ks magnitude distribution of asymptotic giant branch stars provides important constraints on the spatial variation of metallicity and mean-age of the stellar population of galaxies. Here, I present results of the investigation of these…
Purpose: RR Lyrae stars are important distance indicators. They are usually present in globular clusters where they were first discovered. The study of their properties and distribution in our Galaxy and external galaxies constitutes a…
In this review I will discuss recent developments on the topic of resolved Asymptotic Giant Branch (AGB) stars and Long Period Variables (LPVs) in our Galaxy, the Magellanic Clouds, and the Local Group in general. Since the main…
The determination of accurate chemical abundances of planetary nebulae (PN) in different galaxies allows us to obtain important constraints of chemical evolution models for these systems. We have a long term program to derive abundances in…
RR Lyrae variables are excellent population II distance indicators thanks to their well-defined period-luminosity relations (PLRs) at infrared wavelengths. We present results of near-infrared (NIR) monitoring of Galactic globular clusters…
We examine the properties of the Magellanic Bridge connecting the Large and Small Magellanic Clouds using ab-type RR Lyrae variables from the extensive dataset of the Optical Gravitational Lensing Experiment (OGLE), Phase IV data release.…
Although many globular clusters (GCs) have been identified in the Galaxy, their population is estimated to be incomplete, especially in regions with strong crowding and interstellar extinction such as the Galactic bulge and plane.RR Lyrae…
We discuss in detail the pulsation properties of variable stars in globular clusters (GCs) and in Local Group (LG) dwarf galaxies. Data available in the literature strongly support the evidence that we still lack a complete census of…
We infer the UV luminosities of Local Group galaxies at early cosmic times ($z \sim 2$ and $z \sim 7$) by combining stellar population synthesis modeling with star formation histories derived from deep color-magnitude diagrams constructed…
The catalogue of the Johnson-Cousins B,V and I light curves obtained for 162 variable stars (135 RR Lyrae, 4 candidate Anomalous Cepheids, 11 Classical Cepheids, 11 eclipsing binaries and 1 delta Scuti star) in two areas close to the bar of…
The Large Magellanic Cloud (LMC) is widely considered a corner-stone of the astronomical distance scale, however a difference of 0.2-0.3 mag exists in its distance as predicted by the "short" and "long" distance scales. Distances to the LMC…
A comparison is made between the age-metallicity relation obtained from four different types of studies: F and G stars in the Solar Neighbourhood, analysis of open clusters, galactic structure studies with the stellar population synthesis…
The Local Group provides an interesting and representative sample of galaxies in the rest of the Universe. The high accuracy with which many problems can be addressed in Local Group galaxies is of paramount importance for understanding…
Preliminary results of the ongoing search for symbiotic binary stars in the Local Group of Galaxies are presented and discussed.
We have used photometric data on almost 91 000 fundamental-mode RR Lyrae stars (type RRab) detected by the OGLE survey to investigate properties of old populations in the Milky Way. Based on their metallicity distributions, we demonstrate…
Context: The Hubble tuning fork diagram has always been the preferred scheme for classification of galaxies. It is based on morphology only. At the opposite, biologists have long taken into account the genealogical relatedness of living…
Here we describe some of our latest results from measuring detailed abundances in Local Group dwarf galaxies with VLT. Combining spectroscopic abundances with Colour-Magnitude diagrams allows the effective measurement of detailed chemical…