Related papers: Star formation in metal-poor gas clouds
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…
In cold dark matter cosmological models, the first stars to form are believed to do so within small protogalaxies. We wish to understand how the evolution of these early protogalaxies changes once the gas forming them has been enriched with…
Does star formation proceed in the same way in large spirals such as the Milky Way and in smaller chemically younger galaxies? Earlier work suggests a more rapid transformation of H$_2$ into stars in these objects but (1) a doubt remains…
We study the relationship between the H2 and CO abundances in simulated molecular clouds using a fully dynamical model of magnetized turbulence coupled to a detailed chemical network. We find that the CO-to-H2 conversion factor for a given…
The first galaxies contain stars born out of gas with little or no metals. The lack of metals is expected to inhibit efficient gas cooling and star formation but this effect has yet to be observed in galaxies with oxygen abundance relative…
We present observations of CO(3-2) in 13 main-sequence $z=2.0-2.5$ star-forming galaxies at $\log(M_*/M_{\odot})=10.2-10.6$ that span a wide range in metallicity (O/H) based on rest-optical spectroscopy. We find that CO(3-2)/SFR decreases…
[abridged] The star formation rates (SFR) of low-metallicity galaxies depend sensitively on the gas metallicity, because metals are crucial to mediating the transition from intermediate-temperature atomic gas to cold molecular gas, a…
We test some ideas for star formation relations against data on local molecular clouds. On a cloud by cloud basis, the relation between the surface density of star formation rate and surface density of gas divided by a free-fall time,…
We explore the minimal conditions which enable the formation of metal-enriched solar and sub-solar mass stars. We find that in the absence of dust grains, gas fragmentation occurs at densities nH ~ [10^4-10^5]cm^{-3} when the metallicity…
A reliable estimate of the molecular gas content in galaxies plays a crucial role in determining their dynamical and star-forming properties. However, H2, the dominant molecular species, is difficult to observe directly, particularly in the…
We study star cluster formation in various environments with different metallicities and column densities by performing a suite of three-dimensional radiation hydrodynamics simulations. We find that the photoionization feedback from massive…
High-resolution CO maps of 9 molecular clouds in IC 10 are combined with the new measurement of the distance to this nearby metal poor galaxy to measure accurately the CO-to-H2 conversion factor. The result for IC 10 is combined with…
The most common means of converting an observed CO line intensity into a molecular gas mass requires the use of a conversion factor (Xco). While in the Milky Way this quantity does not appear to vary significantly, there is good reason to…
The theory for the formation of the first population of stars (Pop III) predicts an initial mass function (IMF) dominated by high-mass stars, in contrast to the present-day IMF, which tends to yield mostly stars with masses less than 1…
We describe how star formation is expected to proceed in the early metal-free Universe, focusing on the very first generations of stars. We then discuss how the star formation process may change as the effects of metallicity, external…
Simulations of the formation of Population III (Pop III) stars suggest that they were much more massive than the Pop II and Pop I stars observed today. This is due to the collapse dynamics of metal-free gas, which is regulated by the…
The star-forming ability of a molecular cloud depends on the fraction of gas it can cycle into the dense-phase. Consequently, one of the crucial questions in reconciling star-formation in clouds is to understand the factors that control…
Determining the efficiency with which gas is converted into stars in galaxies requires an accurate determination of the total reservoir of molecular gas mass. However, despite being the most abundant molecule in the Universe, H$_2$ is…
The James Webb Space Telescope (JWST) has revealed unexpectedly rapid galaxy assembly in the early universe, in tension with models of star and galaxy formation. In the gas conditions typical of early galaxies, particularly their low…
The formation of stars is a key process in the early universe with far reaching consequences for further cosmic evolution. While stars forming from truly primordial gas are thought to be considerably more massive than our Sun, stars in the…