Related papers: Updated properties of the old open cluster Melotte…
We report the results of photometric monitoring of the Melotte 66 field in BVI filters. Ten variables were identified with nine being new discoveries. The sample includes eight eclipsing binaries of which four are W UMa type stars, one star…
We present wide field photometry of the Galactic Globular Cluster M~22 in the B, V and I passbands for more than 186,000 stars. The study is complemented by the photometry in two narrowband filters centered on H$_{\alpha}$ and the adjacent…
Galactic open clusters are since long recognized as one of the best tools for investigating the radial distribution of iron and other metals. We employed FLAMES at VLT to collect UVES spectra of bright giant stars in a large sample of open…
NGC 6791 is an old, metal-rich star cluster normally considered to be a disk open cluster. Its red giant branch is broad in color yet, to date, there is no evidence for a metallicity spread among its stars. The turnoff region of the main…
NGC 663 is a young, moderately rich open cluster, known to contain one of the largest fractions of Be stars among all galactic clusters. In this work we present CCD uvby-beta photometry for stars in its central area. We have used these data…
Observations of massive stars in young open clusters (< ~8 Myr) have shown that a majority of them are in binary systems, most of which will interact during their life. Populations of massive stars older than ~20 Myr allow us to probe the…
One of the most unexpected results in the field of stellar populations of the last few years, is the discovery that some Magellanic-Cloud globular clusters younger than ~400 Myr, exhibit bimodal main sequences (MSs) in their color-magnitude…
We have carried out high-precision photometry on a large number of archival HST images of the Galactic globular cluster NGC 6752, to search for signs of multiple stellar populations. We find a broadened main sequence, and demonstrate that…
We present a catalog of 2,990 extended sources in a 1deg x1deg area centered on M33 using the MegaCam camera on the 3.6m Canada-France-Hawaii telescope (CFHT). The catalog includes 599 new candidate stellar clusters, 204 previously…
We use HST observations to study the LMC's young cluster NGC1844. We estimate the fraction and the mass-ratio distribution of photometric binaries and report that the main sequence presents an intrinsic breadth which can not be explained in…
We have analyzed multi-passband photometric observations, obtained with the {\it Hubble Space Telescope}, of the massive ($1.8 \times 10^5 M_\odot$), intermediate-age (1.8 Gyr-old) Large Magellanic Cloud star cluster NGC 1783. The…
We present a photometric study of M13 multiple stellar populations over a wide field of view, covering approximately 6.5 half-light radii, using archival Isaac Newton Telescope observations to build an accurate multi-band Str\"omgren…
We present photometric analysis of twelve Galactic open clusters and show that the same multiple-population phenomenon observed in Magellanic Clouds (MCs) is present in nearby open clusters. Nearly all the clusters younger than $\sim$2.5…
We report on the spread of [Fe/H] values in the massive Large Magellanic Cloud cluster NGC1978, recently confirmed to harbor multiple populations of nearly the same age. We used accurate Stromgren photometry of carefully selected cluster…
We examine four ancient Large Magellanic Cloud (LMC) globular clusters (GCs) for evidence of multiple stellar populations using the Advanced Camera for Surveys and Wide Field Camera 3 on the Hubble Space Telescope Programme GO-14164. NGC…
A few years ago we started an observational campaign aimed at the thorough study of the massive and remote globular cluster NGC2419. We have used the collected data, e.g., to test alternative theories of gravitation, to constrain the…
We discuss new photometry from high-resolution images of 7 intermediate-age (1-2 Gyr) star clusters in the Large Magellanic Cloud taken with the Advanced Camera for Surveys on board the Hubble Space Telescope. We fit color-magnitude…
We present a detailed analysis of the upper main sequence of the 1.3 Gyr old open cluster Trumpler 20. High accuracy BV photometry combined with the Very Large Telescope/FLAMES medium-resolution spectroscopy of 954 stars is essential to…
Stars in open clusters are powerful probes of the intervening Galactic magnetic field, via background starlight polarimetry, because they provide constraints on the magnetic field distances. We use 2MASS photometric data for a sample of 31…
Recent studies have shown that the observed main-sequence turn-off (MSTO) in colour-magnitude diagrams of intermediate age (1-2 Gyr) clusters in the LMC are broader than would be nominally expected for a simple stellar population. This has…