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Observed molecular clouds often appear to have very low star formation efficiencies and lifetimes an order of magnitude longer than their free-fall times. Their support is attributed to the random supersonic motions observed in them. We…

天体物理学 · 物理学 2010-10-28 Ralf S. Klessen , Fabian Heitsch , Mordecai-Mark Mac Low

Understanding the star formation process 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, modulated by…

天体物理学 · 物理学 2007-05-23 Ralf S. Klessen

The formation and evolution of galactic disks are complex phenomena, where gas and star dynamics are coupled through star formation and the related feedback. The physical processes are so numerous and intricate that numerical models focus,…

天体物理学 · 物理学 2009-11-07 B. Semelin , F. Combes

(ABBREVIATED) Understanding the formation of stars in galaxies is central to much of modern astrophysics. In this review the relation between interstellar turbulence and star formation is discussed. Supersonic turbulence can provide support…

天体物理学 · 物理学 2009-09-29 Ralf S. Klessen

Complex turbulent motions of magnetized gas are ubiquitous in the interstellar medium. The source of this turbulence, however, is still poorly understood. Previous work suggests that compression caused by supernova shockwaves, gravity, or…

星系天体物理 · 物理学 2020-02-26 Ankush Mandal , Christoph Federrath , Bastian Körtgen

We compute the star formation rate (SFR) in molecular clouds (MCs) that originate {\it ab initio} in a new, higher-resolution simulation of supernova-driven turbulence. Because of the large number of well-resolved clouds with…

星系天体物理 · 物理学 2017-05-10 Paolo Padoan , Troels Haugbølle , Åke Nordlund , Søren Frimann

How does turbulence contribute to the formation and structure of the dense interstellar medium (ISM)? Molecular clouds are dense, high-pressure objects. It is usually argued that gravitational confinement causes the high pressures, and that…

天体物理学 · 物理学 2017-01-18 Mordecai-Mark Mac Low

We suggest that molecular cloud (MC) turbulence is a consequence of the very process of MC formation by collisions of larger-scale flows in the diffuse atomic gas, which generate turbulence in the accumulated gas through bending- mode…

天体物理学 · 物理学 2007-05-23 Enrique Vazquez-Semadeni , Javier Ballesteros-Paredes , Ralf Klessen

We investigate the thermal and dynamical evolution of primordial gas clouds in the universe after decoupling. Comparing the time-scale of dynamical evolution with that of fragmentation, we can estimate the typical fragmentation scale. We…

天体物理学 · 物理学 2009-10-31 Ryoichi Nishi , Hajime Susa , Hideya Uehara , Masako Yamada , Kazuyuki Omukai

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…

星系天体物理 · 物理学 2017-02-22 Erin Maier , Li-Hsin Chien , Deidre A. Hunter

We review current understanding of star formation, outlining an overall theoretical framework and the observations that motivate it. A conception of star formation has emerged in which turbulence plays a dual role, both creating…

天体物理学 · 物理学 2008-11-26 Christopher F. McKee , Eve C. Ostriker

We present N-PDFs of 29 Galactic regions obtained from Herschel imaging at high angular resolution, covering diffuse and quiescent clouds, and those showing low-, intermediate-, and high-mass star formation (SF), and characterize the cloud…

Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of…

天体物理学 · 物理学 2008-11-26 Richard B. Larson

In the multi-scale view of the star formation process the material flows from large molecular clouds down to clumps and cores. In this paradigm it is still unclear if it is gravity or turbulence that drives the observed supersonic…

星系天体物理 · 物理学 2022-09-21 A. Traficante , G. A. Fuller , A. Duarte-Cabral , D. Elia , M. H. Heyer , S. Molinari , N. Peretto , E. Schisano

Whilst the star formation rate (SFR) of molecular clouds and galaxies is key in understanding galaxy evolution, the physical processes which determine the SFR remain unclear. This uncertainty about the underlying physics has resulted in…

星系天体物理 · 物理学 2015-05-14 Diane M. Salim , Christoph Federrath , Lisa J. Kewley

We investigate the properties of highly compressible turbulence, the compressibility arising from a small effective polytropic exponent $\gamma_e$ due to cooling. In the limit of small $\gamma_e$, the density jump at shocks is shown to be…

天体物理学 · 物理学 2009-10-28 E. Vazquez-Semadeni , T. Passot , A. Pouquet

We investigate the formation and evolution of giant molecular clouds (GMCs) by the collision of convergent warm neutral medium (WNM) streams in the interstellar medium, in the presence of magnetic fields and ambipolar diffusion (AD),…

We present a detailed computational study of the assembly of protostellar disks and massive stars in molecular clouds with supersonic turbulence. We follow the evolution of large scale filamentary structures in a cluster-forming clump down…

天体物理学 · 物理学 2009-11-11 Robi Banerjee , Ralph E. Pudritz , Dave W. Anderson

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…

天体物理学 · 物理学 2009-07-09 Lars Hernquist , Volker Springel

We present a model that unifies the cosmic star formation rate (CSFR), obtained through the hierarchical structure formation scenario, with the (Galactic) local star formation rate (SFR). It is possible to use the SFR to generate a CSFR…

星系天体物理 · 物理学 2017-11-15 Carolina Gribel , Oswaldo D. Miranda , Jose Williams Vilas-Boas