Related papers: On the Paradoxical Impact of Blending by Red Clump…
Two problems about the faintest Small Magellanic Cloud (SMC) Cepheids are addressed. On one hand evolutionary tracks fail to cross the Cepheid Instability Strip for the highest magnitudes (i.e. I-mag~17) where Cepheids are observed;…
We have derived high spatial resolution metallicity maps covering $\sim$42 deg$^2$ across the Small Magellanic Cloud (SMC) in an attempt to understand its metallicity distribution and gradients up to a radius of $\sim$ 4$^{\circ}$. Using…
Studies of gravitational microlensing effects require the estimation of their detection efficiency as soon as one wants to quantify the massive compact objects along the line of sight of source targets. This is particularly important for…
A significant fraction of high redshift star-forming disc galaxies are known to host giant clumps, whose nature and role in galaxy evolution are yet to be understood. In this work we first present a new method based on neural networks to…
We used the OGLE-II and OGLE-III photometry of red giants in the Large Magellanic Cloud to select and study objects revealing ellipsoidal variability. We detected 1546 candidates for long period ellipsoidal variables and 121 eclipsing…
We provide a grid of PHOENIX spectra of red giant and supergiant stars, that extend through optical and near-IR wavelengths. For the first time, models are also provided with modified surface abundances of C, N and O, as a step towards…
We present [Fe/H] and [Ca/Fe] of $\sim600$ red giant branch (RGB) members of the globular cluster $\omega$ Centauri. We collect medium-resolution ($R\sim2000$) spectra using the Blanco 4 m telescope at the Cerro Tololo Inter-American…
There is strong evidence that the period-luminosity (PL) relation for the Large Magellanic Cloud (LMC) Cepheids shows a break at a period around 10 days. Since the LMC PL relation is extensively used in distance scale studies, the…
We have calibrated the Tip of the Red Giant Branch (TRGB) using our recent catalog of homogeneous, high-accuracy Globular Cluster (GC) distances. The GC distances were determined by a global joint fit to optical period-Wesenheit relations…
Current observations of the Galactic Center (GC) seem to display a core-like distribution of bright stars from $\sim 5"$ inwards. On the other hand, we observe young, massive stars at the GC, with roughly 20-50\% of them in a disc, mostly…
We have tabulated lists of upper red giant, horizontal, and asymptotic giant branch (RGB, HB, AGB) stars in the globular cluster M5 that are complete to over 10' from the core for the RGB and AGB samples, and 8' for the HB sample. The large…
We demonstrate that failure to properly account for stellar evolution can bias results in determinations of the spatial morphology of Galactic bulge stars, focusing on the question of whether or not the X-shape is more pronounced among the…
We present observational estimates of the magnitude difference between the luminosity function RGB bump and the HB (Delta(bump-zahb)), and of star counts in the bump region (R_bump), for a sample of 54 Galactic globular clusters (GCs)…
State-of-the art photometric measurements of extragalactic Cepheids account for the mean additional light due to chance superposition of Cepheids on crowded backgrounds through the use of artificial star measurements. However, light from…
We present a precise determination of the apparent magnitude of the tip of the red giant branch (TRGB) in the I (0.8 micron), J (1.25 micron), and K_S (2.15 micron) bands from the luminosity function of a sample of data extracted from the…
We use synthetic photometry from Gaia DR3 BP and RP spectra for a large selected sample of stars in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) to derive the magnitude of the Red Giant Branch (RGB) tip for these two…
We present the first part of a new catalog of variable stars (OIII-CVS) compiled from the data collected in the course of the third phase of the Optical Gravitational Lensing Experiment (OGLE-III). In this paper we describe the catalog of…
We perform a detailed analysis of Cepheids in NGC 4258, Magellanic Clouds and Milky Way in order to verify the reliability of the theoretical scenario based on a large set of nonlinear convective pulsation models. We derive Wesenheit…
We have tested the reliability of the red giant branch (RGB) as a metallicity indicator accounting for observational errors as well as the complexity of star formation histories (SFHs) and chemical evolution histories observed in various…
Mass-loss rates currently in use for hot, massive stars have recently been seriously questioned, mainly because of the effects of wind clumping. We investigate the impact of clumping on diagnostic ultraviolet resonance and optical…