Related papers: Gravity, Turbulence, and Star Formation
To explore the potential role of gravity, turbulence and magnetic fields in high-mass star formation in molecular clouds, this study revisits the velocity dispersion--size ($\sigma$--$L$) and density--size ($\rho$--$L$) scalings and the…
Clusters of galaxies form through major merger and/or absorption of smaller groups. In fact, some characteristic structures such as cold fronts, which are likely relevant to moving substructures, are found by {\it Chandra}. It is expected…
Observations and theories of the stellar initial mass function are reviewed. The universality and large total mass range of the power law portion of the IMF suggest a connection between stellar mass and cloud structure. The fractal patterns…
Although the theoretical understanding of the nonlinear gravitational clustering has greatly advanced in the last decades, in particular by the outstanding improvement on numerical N-body simulations, the physics behind this process is not…
We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the…
The majority of stars are thought to form in clusters. Cluster formation in dense clumps of molecular clouds is strongly influenced, perhaps controlled, by supersonic turbulence. We have previously shown that the turbulence in regions of…
Understanding star formation is problematic as it originates in the large scale dynamics of a galaxy but occurs on the small scale of an individual star forming event. This paper presents the first numerical simulations to resolve the star…
This two-part review summarizes interstellar turbulence and its implications. The first part begins with diagnostics and energy sources. Turbulence theory is considered in detail, including the basic fluid equations, solenoidal and…
We investigate the gravitational instability of galactic discs, treating stars and cold interstellar gas as two distinct components, and taking into account the phenomenology of turbulence in the interstellar medium (ISM), i.e. the…
Supersonic gas turbulence is a ubiquitous property of the interstellar medium. The level of turbulence, quantified by the gas velocity dispersion ($\sigma_{\rm g}$), is observed to increase with the star formation rate (SFR) of a galaxy,…
We discuss HD and MHD compressible turbulence as a cloud-forming and cloud-structuring mechanism in the ISM. Results from a numerical model of the turbulent ISM at large scales suggest that the phase-like appearance of the medium, the…
Turbulence is ubiquitous in the interstellar medium (ISM) of the Milky Way and other spiral galaxies. The energy source for this turbulence has been much debated with many possible origins proposed. The universality of turbulence, its…
(Abridged) The formation of molecular clouds (MCs) from the diffuse interstellar gas appears to be a necessary step for star formation, as young stars invariably occur within them. However, the mechanisms controlling the formation of MCs…
Recent progress in the understanding of star formation is summarized. A consistent picture is emerging where molecular clouds form with turbulent velocity fields and clumpy substructure, imprinted already during their formation. The clouds…
We review the properties of turbulent molecular clouds (MCs), focusing on the physical processes that influence star formation (SF). MC formation appears to occur during large-scale compression of the diffuse ISM driven by supernovae,…
We invoke star formation triggered by cloud-cloud collisions to explain global star formation rates of disk galaxies and circumnuclear starbursts. Previous theories based on the growth rate of gravitational perturbations ignore the…
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 generation mechanism of compressible fluid turbulence at kiloparsec scales in the Interstellar Medium (ISM) is a long-lasting puzzle. In this work, we explore the nature of large-scale turbulence in the external spiral galaxy NGC~6946.…
The origin of non-thermal motions in massive star forming regions can be ascribed to turbulence acting against the gravitational collapse, or to the self-gravity itself driving the rapid global collapse. The dependence between velocity…
Giant Molecular Clouds (GMCs) are observed to be turbulent, but theory shows that without a driving mechanism turbulence should quickly decay. The question arises by which mechanisms turbulence is driven or sustained. It has been shown that…