Effective star formation rates in tabular form are computed which yield a prescription for the star formation activity in model galaxies as a function of ambient density, metallicity, and stellar feedback. The effects of supernova explosions on the thermal balance of the Interstellar Medium (ISM) and the presence of a multi-phase ISM are explicitly included. The resulting grid of models can be ...

Mergers of massive gas-rich galaxies trigger violent starbursts that – over timescales of > 100 Myr and regions > 10 kpc – form massive and compact star clusters comparable in mass and radii to Galactic globular clusters. The star formation efficiency is higher by 1 – 2 orders of magnitude in these bursts than in undisturbed spirals, irregulars or even BCDs. We ask the question if star formatio...

We explore how the expulsion of gas from star cluster forming cloud cores due to supernova explosions affects the shape of the initial clustermass function, that is, themass function of star clusterswhen effects of gas expulsion are over. We demonstrate that if the radii of cluster-forming gas cores are roughly constant over the coremass range, as supported by observations, then more massive co...

The discovery that the short-lived radionucleide Fe was present in the oldest meteorites suggests that the formation of the Earth closely followed the death of a massive star. I discuss three astrophysical origins: winds from an AGB star, injection of supernova ejecta into circumstellar disks, and induced star formation on the boundaries of HII regions. I show that the first two fail to match t...

The results of UBV and Hα imaging of a large sample of isolated dwarf irregular galaxies are interpreted in the context of composite stellar population models. The observed optical colors are best fit by composite stellar populations which have had approximately constant star formation rates for at least 10 Gyr. The galaxies span a range of central surface brightness, from 20.5 to 25.0 mag arcs...

Ring galaxies are specific types of interacting galaxies in which a smaller galaxy has passed through the center of the disk of another larger galaxy. The intrusion of the smaller galaxy causes the structure of the larger galaxy to compress as the smaller galaxy falls through, and to recoil back after the smaller galaxy passes through, hence the ring-like shape. In our research, we studied the ...

We provide a brief overview of recent advances and outstanding issues in simulations of interstellar turbulence, including isothermal models for interior structure of molecular clouds and larger-scale multiphase models designed to simulate the formation of molecular clouds. We show how self-organization in highly compressible magnetized turbulence in the multiphase ISM can be exploited in simpl...

Over the past ten years, the concept of adaptive optics has evolved from early experimental stages to a standard observing tool now available at almost all major optical and near-infrared telescope facilities. Adaptive optics will also be essential in exploiting the full potential of the large optical/infrared interferometers currently under construction. Both observations with high-angular res...

We study how interactions between galaxies affect star formation within them by considering a sample of almost 1500 of the nearest galaxies, all within a distance of ∼45 Mpc. We use the far-IR emission to define the massive star formation rate (SFR), and then normalise the SFR by the stellar mass of the galaxy to obtain the specific star formation rate (SSFR). We explore the distribution of (S)...

Using integrated optical spectrophotometry for 412 star-forming galaxies at z ∼ 0, and fiber-aperture spectrophotometry for 120, 846 SDSS galaxies at z ∼ 0.1, we investigate the Hα λ6563, Hβ λ4861, [O ii] λ3727, and [O iii] λ5007 nebular emission lines and the U -band luminosity as quantitative star-formation rate (SFR) indicators. We demonstrate that the extinction-corrected Hα λ6563 luminosit...