Over the past years observations of young and populous star clusters have shown that the stellar IMF appears to be an invariant featureless Salpeter power-law with an exponent α = 2.35 for stars more massive than a few Msolar. A consensus has also emerged that most, if not all, stars form in stellar groups and star clusters, and that the mass

Recent research regarding the star formation in star clusters on galaxy wide scales indicates that, in the hypothesis that all stars are born within clusters, the supposedly universal initial stellar mass function (IMF) within young star clusters, does not necessarily yield the same IMF for whole galaxies. As star clusters also follow an embedded

The ACS Survey of Galactic Globular Clusters is a Hubble Space Telescope (HST) Treasury program designed to provide a new large, deep and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters'

We analyzed far-UV (FUSE), UV (HST, IUE) and optical spectra of hot massive stars in the Milky Way with non-LTE, line-blanketed models with sphericity and expanding winds. We were able to reconcile previously discrepant diagnostics from Hα to highly ionized transitions (e.g. OVI and NV) with a revised treatement of soft X-rays from shocks and

Close but detached binaries consisting of a white dwarf and a main sequence star are important objects for the understanding of the evolution of compact binaries such as cataclysmic variables (CVs), supersoft X-ray sources, and X-ray binaries. Since they are still detached, no accretion takes place, and both stars can be studied without the strong

The duration of a starburst is a fundamental parameter affecting the evolution of galaxies yet, to date, observational constraints on the durations of starbursts are not well established. We present the recent star formation histories (SFHs) of 18 nearby dwarf galaxies and rigorously quantify the duration of their starburst events using a uniform