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The zero-age main sequence (ZAMS) is a critical phase for stellar angular momentum evolution, as stars transition from contraction-dominated spin-up to magnetic wind-dominated spin-down. We present the first robust observational constraints…

Globular Clusters (GCs) in the Milky Way are the primary laboratories for establishing the ages of the oldest stellar populations and for measuring the color-magnitude relation of stars. In infrared (IR) color-magnitude diagrams (CMDs), the…

Extended MS turn-offs are features commonly found in the colour-magnitude diagrams of young and intermediate age (less than about 2 Gyr) massive star clusters, where the MS turn-off is broader than can be explained by photometric…

We present a detailed stellar clustering analysis with the application of the two-point correlation function on distinct young stellar ensembles. Our aim is to understand how stellar systems are assembled at the earliest stages of their…

Early release science observations of the cluster NGC3603 with the WFC3 on the refurbished HST allow us to study its recent star formation history. Our analysis focuses on stars with Halpha excess emission, a robust indicator of their…

In the past years, we have undertaken an extensive investigation of LMC and SMC star clusters based on HST data. We present photometry and astrometry of stars in 101 fields observed with the WFC/ACS, UVIS/WFC3 and NIR/WFC3 cameras. These…

Colour-magnitude diagrams (CMD) of the SMC star cluster NGC419, derived from HST/ACS data, reveal a well-delineated secondary clump located below the classical compact red clump typical of intermediate-age populations. We demonstrate that…

Extended main sequence turn-offs (eMSTOs) are a common feature in color-magnitude diagrams (CMDs) of young and intermediate-age star clusters in the Magellanic Clouds. The nature of eMSTOs is still debated. The most popular scenarios are…

We present an analysis of the rotation of young stars in the associations Cepheus OB3b, NGC 2264, NGC 2362 and the Orion Nebula Cluster (ONC). We discover a correlation between rotation rate and position in a colour-magnitude diagram (CMD)…

Using a combination of high-resolution Hubble Space Telescope/WFPC2 observations, we explore the physical properties of the stellar populations in two intermediate-age star clusters in the Large Magellanic Cloud, NGC 1831 and NGC 1868,…

Galaxy interactions are known to trigger starbursts. The young star clusters formed in mergers may be young globular clusters. The ages of these young star clusters yield the timing of interaction-triggered star formation and provide an…

The photometric properties of main sequence (MS) and pre-main sequence (PMS) stars in the young cluster Haffner 16 are examined using images recorded with the Gemini South Adaptive Optics Imager (GSAOI) and corrected for atmospheric…

We demonstrate the feasibility of detecting directly low mass stars in unresolved super-star clusters with ages < 10 Myr using near-infrared spectroscopy at modest resolution (R ~ 1000). Such measurements could constrain the ratio of high…

The color-magnitude diagram (CMD) of globular cluster NGC1651 has special structures including a broad main sequence, an extended main sequence turn-off and an extended red giant clump. The reason for such special CMDs remains unclear. In…

[ABRIDGED] The LMC star cluster system offers the unique opportunity to independently check the accuracy of age and mass determinations based on a number of complementary techniques, including isochrone analysis. Using our sophisticated…

We combine a number of recent studies of the extended main sequence turn-off (eMSTO) phenomenon in intermediate age stellar ($1-2$ Gyr) clusters in the Large Magellanic Cloud (LMC) in order to investigate its origin. By employing the…

A large number of intermediate-age (~1-2-Gyr old) globular clusters (GCs) in the Large and the Small Magellanic Cloud (MC) exhibit either bimodal or extended main-sequence (MS) turn off and dual red clump. Moreover, recent papers have shown…

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 present the results of our investigation of the intermediate-age star cluster BS 90, located in the vicinity of the HII region N 66 in the SMC, observed with HST/ACS. The high-resolution data provide a unique opportunity for a very…

We present ground-based B and R-band color-magnitude diagrams (CMDs), reaching the oldest main-sequence turnoffs with good photometric accuracy for twelve fields in the Small Magellanic Cloud (SMC). Our fields, located between ~1 and ~4…