Related papers: Fractional Stars
We introduce a simple model to explore the star formation histories of disk galaxies. We assume that the disk origins and grows by continuous gas infall. The gas infall rate is parametrized by the Gaussian formula with one free parameter:…
Sub-virial gravitational collapse is one mechanism by which star clusters may form. Here we investigate whether this mechanism can be inferred from observations of young clusters. To address this question, we have computed SPH simulations…
Optically thin cooling gas at most temperatures above 30K will make condensations by pressure pushing material into cool dense regions. This works without gravity. Cooling condensations will flatten and become planar/similarity solutions.…
Intermediate mass stars and stellar remnants often host planets, and these dynamical systems evolve because of mass loss and tides. This paper considers the combined action of stellar mass loss and tidal dissipation on planetary orbits in…
A fraction of the dense cores within a turbulent molecular cloud will eventually collapse to form stars. Identifying the physical criteria for instability and analyzing critical core properties is therefore necessary to star formation…
Sheet-like clouds are common in turbulent gas and perhaps form via collisions between turbulent gas flows. Having examined the evolution of an isothermal shocked slab in an earlier contribution, in this work we follow the evolution of a…
We study the formation of giant dense cloud complexes and of stars within them by means of SPH numerical simulations of the mildly supersonic collision of gas streams (``inflows'') in the warm neutral medium (WNM). The resulting…
The collapse of marginally Jeans unstable primordial gas clouds in the presence of UV radiation field is discussed. Assuming that the dynamical collapse proceeds approximately in an isothermal self-similar fashion, we investigate the…
Stars in galaxies form in giant molecular clouds that coalesce when the atomic hydrogen is converted into molecules. There are currently two dominant models for what property of the galactic disk determines its molecular fraction: either…
We examine the cosmic evolution of a stellar initial mass function (IMF) in galaxies that varies with the Jeans mass in the interstellar medium, paying particular attention to the K-band stellar mass to light ratio (M/L_K) of present-epoch…
One of the outstanding puzzles about star formation is why it proceeds so slowly. Giant molecular clouds convert only a few percent of their gas into stars per free-fall time, and recent observations show that this low star formation rate…
The current generation of millimeter interferometers have revealed a population of compact (r <~ 0.1 pc), massive (M ~ 100 Msun) gas cores that are the likely progenitors of massive stars. I review models for the evolution of these objects…
In this paper we examine aspects of primordial star formation in a gravitino warm dark matter universe with a cosmological constant. We compare a set of simulations using a single cosmological realization but with a wide range of warm dark…
Star complexes are the largest globular regions of star formation in galaxies. If there is a spiral density wave, nuclear ring, tidal arm, or other well-defined stellar structure, then gravitational instabilities in the gaseous component…
The remarkably filamentary spatial distribution of young stars in the Taurus molecular cloud has significant implications for understanding low-mass star formation in relatively quiescent conditions. The large scale and regular spacing of…
Star formation is inefficient. Only a few percent of the available gas in molecular clouds forms stars, leading to the observed low star formation rate (SFR). The same holds when averaged over many molecular clouds, such that the SFR of…
The origin of the observed morphological and kinematic substructure of young star forming regions is a matter of debate. We offer a new analysis of data from simulations of globally gravitationally collapsing clouds of progenitor gas to…
The formation of stellar clusters dictates the pace at which galaxies evolve, and solving the question of their formation will undoubtedly lead to a better understanding of the Universe as a whole. While it is well known that star clusters…
The nature of turbulence in molecular clouds is one of the key parameters that control star formation efficiency: compressive motions, as opposed to solenoidal motions, can trigger the collapse of cores, or mark the expansion of Hii…
In the first article of this series, we have used the ergodic theory to assess the validity of a statistical approach to characterize various properties of star-forming molecular clouds (MCs) from a limited number of observations or…