Observations of GRB host galaxies and their environments in general can provide valuable clues about the nature of progenitors. Bursts are associated with faint, 〈R〉 ∼ 25 mag, galaxies at cosmological redshifts, 〈z〉 ∼ 1. The host galaxies span a range of luminosities and morphologies, and appear to be broadly typical for the normal, evolving, actively star-forming galaxy populations at comparab...

Ground-based UBV photometry of two fields in the northern disk of the LMC are presented. A distance modulus of (m − M)0 = 18.41± 0.04 and an extinction of AV = 0.30 ± 0.05 has been calculated for these fields. The measurable star formation history of the LMC began no more than 12 Gyr ago with a strong star forming episode with [Fe/H] = -1.63 ± 0.10 that accounted for approximately half (by mass...

The stellar population and star clusters around six regions in the Large Magellanic Cloud (LMC) are studied to understand the correlation between star formation and cluster formation rates. We used the stellar data base of the OGLE II LMC survey and the star cluster catalogues. The observed distributions of stellar density in the colour−magnitude diagrams (CMDs) were compared with synthetic one...

We present a comprehensive study of the physical properties of ∼ 10 galaxies with measurable star formation in the SDSS. By comparing physical information extracted from the emission lines with continuum properties, we build up a picture of the nature of star-forming galaxies at z < 0.2. We develop a method for aperture correction using resolved imaging and show that our method takes out essent...

We have derived the star formation history of the Milky Way disk over the last 2 Gyr with a time resolution of 0.05 Gyr from the age distribution diagram of a large sample of open clusters comprising more than 580 objects. By interpreting the age distribution diagram using numerical results from an extensive library of N-body calculations carried out during the last ten years, we reconstruct th...

We present a general star formation law in which the star formation rate depends upon the ef®ciency a and the time-scale t of star formation, and the gas component jg of the surface mass density. The current nominal Schmidt exponent nS for our model is 2 < nS < 3. Based on a gravitational instability parameter QA and another dimensionless parameter fP ˆ …P=Gj 2 c† , where P ˆ pressure and jc ˆ ...

Context. Bright-rimmed clouds (BRCs) are potential examples of triggered star formation regions, in which photoionisation driven shocks caused by the expansion of HII regions induce protostellar collapse within the clouds. Aims. The main purpose of the paper is to establish the level of star formation occuring within a known set of BRCs. A secondary aim is to determine the extent, if any, to wh...

It has been known for more than 30 years that star formation in giant molecular clouds (GMCs) is slow, in the sense that only ∼ 1% of the gas forms stars every free-fall time. This result is entirely independent of any particular model of molecular cloud lifetime or evolution. Here we survey observational data on higher density objects in the interstellar medium, including infrared dark clouds ...

We examine the effects of gas expulsion on initially substructured and out-of-equilibrium star clusters. We perform N-body simulations of the evolution of star clusters in a static background potential before removing that potential to model gas expulsion. We find that the initial star formation efficiency is not a good measure of the survivability of star clusters. This is because the stellar ...

Star formation, a crucial link in the chain of events that led from the early expansion of the universe to the formation of the solar system, continues to play a major role in the evolution of many galaxies. Observational and theoretical studies of regions of ongoing star formation provide insight into the physical conditions and events that must have attended the formation of the solar system....