We study the evolution of stellar content and the chemical enrichment of the universe averaged over the whole population of galaxies by means of a series of chemo–spectrophotometric models that take into account the metallicity and dust obscuration effects. We investigate various classes of cosmic star formation rates (CSFR) histories consistent with current estimations. We are able to reproduc...

The star formation history in IZw18 has been inferred from HST/WFPC2 archival data. This is done by comparing the derived V, B–V and V, V–I color-magnitude diagrams and luminosity functions with synthetic ones, based on various sets of stellar evolutionary tracks. At a distance of 10 Mpc, the stars resolved in the field of IZw18 allow for a lookback time up to 1 Gyr. We find that the main body ...

We present new central stellar velocity dispersion measurements for 428 galaxies in the Palomar spectroscopic survey of bright, northern galaxies. Of these, 142 have no previously published measurements, most being relatively late-type systems with low velocity dispersions (∼<100 km s −1). We provide updates to a number of literature dispersions with large uncertainties. Our measurements are ba...

I explore the hypothesis that many of the unusual aspects of the apparent stellar bar of the Large Magellanic Cloud are the result of viewing a triaxial stellar bulge that is embedded in a highly obscuring thin disk. Specifically, this hypothesis explains the observed off-center position of the bar within the disk, the differing apparent distances of the bar and disk, the near alignment of the ...

We present 3000–10000 Å HST/STIS long-slit spectroscopy of the bright super star cluster A (SSC-A) in the dwarf starburst galaxy NGC 1569. The 0.05 HST angular resolution allows, for the first time, to probe for spatial variations in the stellar population of a ∼ 10M⊙ SSC. Integrated ground-based spectra of SSC-A have previously revealed young Wolf-Rayet (WR) signatures that coexist with featur...

Observational evidence has been mounting over the past decade that at least some luminous (∼ 2L) galaxies have formed nearly all of their stars within a short period of time only 1–2 × 10 years after the Big Bang. These are examples of the first major episodes of star formation in the Universe and provide insights into the formation of the earliest massive galaxies. We have examined in detail t...

We present the initial results of a Hubble Space Telescope/ACS snapshot survey of 16 nearby, edgeon, late-type galaxies covering a range in distance from 2 to 19 Mpc. The images of these galaxies show significant resolved stellar populations. We derive F606W and F814W photometry for >1.2 million stars, and present color-magnitude diagrams which show a mixture of young, intermediate, and old sta...

We present a photometric and spectroscopic study of stellar populations in the X-ray-luminous cluster of galaxies RXJ0142.0+2131 at z = 0.280. This paper analyses the results of high signal-to-noise spectroscopy, as well as g-, r-, and i-band imaging, using the Gemini Multi-Object Spectrograph on Gemini North. Of 43 spectroscopic targets, we find 30 cluster members over a range in color. Centra...