We analyze the star formation activity of an homogeneous LSB dwarf galaxy sample in the Virgo cluster, as a function of the radial velocity relative to the cluster mean velocity and the projected distance from the center of the cluster, using CCD images obtained at the Wise Observatory. The localized Hα emission in the HII regions of this sample is compared to that of an isolated gas-rich sampl...

As part of an ongoing photometric survey of young Magellanic Cloud clusters we identified Be stars in NGC 1818 and a nearby smaller cluster in the Large Magellanic Cloud. The neighbouring cluster does not appear to contain any evolved stars, and its sparsely populated main sequence does not extend to stars as massive as in NGC 1818. Both clusters are younger than the surrounding field populatio...

Light-echo measurements show that SN1987A is 425 pc behind the LMC disk. It is continuing to move away from the disk at 18 kms. Thus, it has been suggested that SN1987A was ejected from the LMC disk. However, SN1987A is a member of a star cluster, so this entire cluster would have to have been ejected from the disk. We show that the cluster was formed in the LMC disk, with a velocity perpendicu...

IUE spectra have been obtained for 15 members of the very young LMC cluster NGC 1850A. The extinction law toward the cluster is similar to the one generally accepted for the 30 Dor region. We derive the effective temperatures and bolometric luminosities to estimate the age and mass for each star. An age spread of 2 to 10 Myr is estimated, suggesting a more or less continuous star formation proc...

Numerical simulations of the dynamical friction suffered by a star cluster near the Galactic center have been performed with a parallelized tree code. Gerhard (2001) has suggested that dynamical friction, which causes a cluster to lose orbital energy and spiral in towards the galactic center, may explain the presence of a cluster of very young stars in the central parsec, where star formation m...

We present CCD photometry and a proper motion study of the young open star cluster, NGC 581 (M 103). Fitting isochrones to the colour magnitude diagram, we found an age of 16 ± 4Myr and a distance of roughly 3 kpc for this cluster. The proper motion study identifies 77 stars of V = 14.5mag or brighter to be cluster members. We combine membership determination by proper motions and statistical f...

We present CCD photometry and a proper motion study of the young open star cluster, NGC 581 (M 103). Fitting isochrones to the colour magnitude diagram, we found an age of 16 ± 4 Myr and a distance of roughly 3 kpc for this cluster. The proper motion study identifies 77 stars of V = 14.5 mag or brighter to be cluster members. We combine membership determination by proper motions and statistical...

We present optical spectroscopy of 16 star clusters in the merging galaxies NGC 4038/39 (”The Antennae”) and supplement this dataset with HST imaging. The age and metallicity of each cluster is derived through a comparison between the observed Balmer and metal line strengths with simple stellar population models. We then estimate extinctions and masses using the photometry. We find that all but...

We report the first star formation history study of Milky Way's nuclear cluster (NSC) that includes observational constraints from a large sample stellar metallicity measurements. These measurements were obtained recent surveys Gemini and VLT 770 late-type stars within central 1.5 pc. measurements, along with photometry spectroscopically derived temperatures, are forward modeled Bayesian infere...