Related papers: Star formation in metal-poor gas clouds
We present a simplified chemical and thermal model designed to allow computationally efficient study of the thermal evolution of metal-poor gas within large numerical simulations. Our main simplification is the neglect of the molecular…
The inner few hundred parsecs of the Milky Way harbours gas densities, pressures, velocity dispersions, an interstellar radiation field and a cosmic ray ionisation rate orders of magnitude higher than the disc; akin to the environment found…
In this paper, I investigate the processes that regulate the rate of star formation in regions of galaxies where the neutral interstellar medium is predominantly composed of non-star-forming HI. In such regions, found today predominantly in…
We investigate the dependence of stellar properties on the initial kinematic structure of the gas in star-forming molecular clouds. We compare the results from two large-scale hydrodynamical simulations of star cluster formation that…
The complexity of physico-chemical models of star formation is increasing, with models that take into account new processes and more realistic setups. These models allow astrochemists to compute the evolution of chemical species throughout…
We present models of the cosmological star formation and metal production history of (proto-)galaxies with varying axis ratios. More massive and/or roughly spherical systems reach the threshold-metallicity for a transition to a multi-phase…
Substellar objects have extremely long life-spans. The cosmological consequence for older objects are low abundances of heavy elements, which results in a wide distribution of objects over metallicity, hence over age. Within their cool…
Over the past decade increasingly robust estimates of the dense molecular gas content in galaxy populations between redshift 0 and the peak of cosmic galaxy/star formation from redshift 1-3 have become available. This rapid progress has…
We have obtained CO(1-0) observations for a sample of 37 interacting galaxy systems, chosen from a parent sample of optically-selected interacting galaxies. The sample observed here spans a large range of interaction strengths and star…
We use numerical simulations to investigate the importance of HD formation and cooling on the first generation of metal-free stars in a LCDM cosmology. We have implemented and tested non-equilibrium HD chemistry in an adaptive mesh…
We utilize Sloan Digital Sky Survey imaging and spectroscopy of ~53,000 star-forming galaxies at z~0.1 to study the relation between stellar mass and gas-phase metallicity. We derive gas-phase oxygen abundances and stellar masses using new…
Shocks may have been prevalent in the early Universe, associated with virialization and supernova explosions, etc. Here, we study thermal evolution and fragmentation of shock-compressed clouds, by using a one-zone model with detailed…
The process of atomic-to-molecular (HI-to-H$_2$) gas conversion is fundamental for molecular-cloud formation and star formation. 21 cm observations of the star-forming region W43 revealed extremely high HI column densities, of 120-180…
We use a sample of 47 homogeneous and high sensitivity CO images taken from the Nobeyama and BIMA surveys to demonstrate that, contrary to common belief, a significant number (~40%) of HI-deficient nearby spiral galaxies are also depleted…
The addition of metals to any gas can significantly alter its evolution by increasing the rate of radiative cooling. In star-forming environments, enhanced cooling can potentially lead to fragmentation and the formation of low-mass stars,…
Metal abundance and its evolution are studied for Mg II quasar absorption line systems from their weak, unsaturated spectral lines using stacked spectra from the archived data of Sloan Digital Sky Survey. They show an abundance pattern that…
We use simple analytic reasoning to identify physical processes that drive the evolution of the cosmic star formation density in cold dark matter universes. Based on our analysis, we formulate a model to characterise the redshift dependence…
The most metal-poor stars found in the Galaxy and in nearby galaxies are witnesses of the early evolution of the Universe. In a general picture in which we expect the metallicity to increase monotonically with time, as a result of the metal…
We present stellar structure and atmosphere models of metal-free stars and examine them from a cosmological point of view. Metal-free stars exhibit high effective temperatures and small sizes relative to metal-enriched stars of equal mass.…
The most usual tracer of molecular gas is line emission from CO. However, the reliability of that tracer has long been questioned in environments different from the Milky Way. We study the relationship between H2 and CO abundances using a…