Related papers: Gravoturbulent Fragmentation
Star formation is enhanced in spiral arms because of a combination of orbit crowding, cloud collisions, and gravitational instabilities. The characteristic mass for the instability is 10^7 Msun in gas and 10^5 Msun in stars, and the…
This chapter reviews the nature of turbulence in the Galactic interstellar medium (ISM) and its connections to the star formation (SF) process. The ISM is turbulent, magnetized, self-gravitating, and is subject to heating and cooling…
All stars are born in molecular clouds, and most in giant molecular clouds (GMCs), which thus set the star formation activity of galaxies. We first review their observed properties, including measures of mass surface density, Sigma, and…
High-mass stars form in protoclusters, where gravo-magnetic processes shape collapsing clouds and clumps to be elongated preferentially perpendicular to magnetic (B) fields. Yet it remains unclear whether gravo-magnetic processes still…
The fragmentation of gas to form stars in molecular clouds is intrinsically linked to the turbulence within them. These internal motions are set at the birth of the cloud and may vary with galactic environment and as the cloud evolves. In…
Context. Traditionally, supersonic turbulence is considered to be one of the most likely mechanisms to slow down the gravitational collapse in dense clumps, thereby enabling the formation of massive stars. However, several recent studies…
[Abridged] Star and planet formation are the complex outcomes of gravitational collapse and angular momentum transport mediated by protostellar and protoplanetary disks. In this review we focus on the role of gravitational instability in…
Our current understanding of the physical processes of star formation is reviewed, with emphasis on processes occurring in molecular clouds like those observed nearby. The dense cores of these clouds are predicted to undergo gravitational…
The fragmentation of molecular clouds (MC) into protostellar cores is a central aspect of the process of star formation. Because of the turbulent nature of super-sonic motions in MCs, it has been suggested that dense structures such as…
Star clusters are known to be formed in turbulent molecular clouds. How turbulence is driven in molecular clouds and what effect this has on star formation is still unclear. We compare a simulation setup with turbulent driving everywhere in…
The morphology and kinematics of molecular clouds (MCs) are best explained as the consequence of super--sonic turbulence. Super--sonic turbulence fragments MCs into dense sheets, filaments and cores and large low density ``voids'', via the…
(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…
The formation of a star is a dynamic process fed by the gravitational collapse of a molecular cloud core. Theoretical models and observations suggest that the majority of this infalling material settles into a protoplanetary disk before…
Understanding the physics of how stars form is a highly-prioritized goal of modern Astrophysics, in part because star formation is linked to both galactic dynamics on large scales and to the formation of planets on small scales. It is…
I present an overview of the hierarchy of structures existing in the interstellar medium (ISM) and the possible mechanisms that cause the fragmentation of one level into the next, with the formation of stars as its last step. Within this…
Understanding the formation of stars in galaxies is central to much of modern astrophysics. For several decades it has been thought that stellar birth is primarily controlled by the interplay between gravity and magnetostatic support,…
The dynamical processes that control star formation in molecular clouds are not well understood, and in particular, it is unclear if rotation plays a major role in cloud evolution. We investigate the importance of rotation in cloud…
The Taurus molecular cloud complex is the paradigm for quiescent, low-density, isolated star formation. Yet the age distribution of its stellar population indicates that star formation is a rapid and dynamic process, inconsistent with the…
Supersonic turbulence fragments the interstellar medium into dense sheets, filaments, cores and large low density voids. The turbulence is driven on large scales, probably predominantly by supernovae. The scaling properties of supersonic…
Conditions for the fragmentation of expanding shells due to gravitational instability are discussed. The self-similar analytical solution is compared with the results of 3-dimensional computer simulations for the expansion into homogeneous…