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The ionizing radiation of massive stars sculpts the surrounding neutral gas into pillar-like structures. Direct signatures of star formation through outflows and jets are observed in these structures, typically at their tips. Recent…

Astrophysics of Galaxies · Physics 2020-10-28 Shyam H. Menon , Christoph Federrath , Pamela Klaassen , Rolf Kuiper , Megan Reiter

We discuss the nature of the velocity dispersion vs. size relation for molecular clouds. In particular, we add to previous observational results showing that the velocity dispersions in molecular clouds and cores are not purely functions of…

We present an analytical model of the relation between the surface density of gas and star formation rate in galaxies and clouds, as a function of the presence of supersonic turbulence and the associated structure of the interstellar…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-06 Florent Renaud , Katarina Kraljic , Frédéric Bournaud

It is believed that turbulence may have a significant impact on star formation and the dynamics and evolution of the molecular clouds in which this occurs. It is also known that non-ideal magnetohydrodynamic effects influence the nature of…

Astrophysics of Galaxies · Physics 2015-06-05 T. P. Downes

Star formation in the Galactic disc is primarily controlled by gravity, turbulence, and magnetic fields. It is not clear that this also applies to star formation near the Galactic Centre. Here we determine the turbulence and star formation…

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…

Astrophysics · Physics 2007-05-23 Enrique Vazquez-Semadeni , Javier Ballesteros-Paredes , Ralf Klessen

Previous studies have shown that star formation depends on the driving of molecular cloud turbulence, and differences in the driving can produce an order of magnitude difference in the star formation rate. The turbulent driving is…

Astrophysics of Galaxies · Physics 2017-01-25 C. A. Herron , C. Federrath , B. M. Gaensler , G. F. Lewis , N. M. McClure-Griffiths , Blakesley Burkhart

It has been recently shown that molecular clouds do not exhibit a unique shape for the column density probability distribution function (Npdf). Instead, clouds without star formation seem to possess a lognormal distribution, while clouds…

This review summarizes the argument for molecular clouds being dominated by turbulence, most likely super-Alfvenic turbulence. Five lines of observational evidence are given: molecular linewidths and line shapes, nonequilibrium chemical…

Astrophysics · Physics 2007-05-23 Mordecai-Mark Mac Low

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.…

Astrophysics of Galaxies · Physics 2023-10-05 Meera Nandakumar , Prasun Dutta

Turbulence can transport angular momentum in protoplanetary disks and influence the growth and evolution of planets. With spatially and spectrally resolved molecular emission line measurements provided by (sub)millimeter interferometric…

Turbulence is thought to be a key driver of the evolution of protoplanetary disks, regulating the mass accretion process, the transport of angular momentum, and the growth of dust particles. We intend to determine the magnitude of the…

Astrophysics of Galaxies · Physics 2015-06-12 S. Guilloteau , A. Dutrey , V. Wakelam , F. Hersant , D. Semenov , E. Chapillon , T. Henning , V. Piétu

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…

Both observational and theoretical research over the past decade has demonstrated that the probability distribution function (PDF) of the gas density in turbulent molecular clouds is a key ingredient for understanding star formation. It has…

Astrophysics of Galaxies · Physics 2018-11-28 Bastian Körtgen , Christoph Federrath , Robi Banerjee

We utilize observations of sub-millimeter rotational transitions of CO from a Herschel Cycle 2 open time program ("COPS", PI: J. Green) to identify previously predicted turbulent dissipation by magnetohydrodynamic (MHD) shocks in molecular…

Astrophysics of Galaxies · Physics 2022-03-17 Rebecca L. Larson , Neal J. Evans , Joel D. Green , Yao-Lun Yang

Molecular clouds are observed to be turbulent, but the origin of this turbulence is not well understood. As a result, there are two different approaches to simulating molecular clouds, one in which the turbulence is allowed to decay after…

Astrophysics · Physics 2009-11-13 Stella S. R. Offner , Richard I. Klein , Christopher F. McKee

Protostellar jets and outflows are signatures of star formation and promising mechanisms for driving supersonic turbulence in molecular clouds. We quantify outflow-driven turbulence through three-dimensional numerical simulations using an…

Instrumentation and Methods for Astrophysics · Physics 2013-04-25 Anthony Moraghan , Jongsoo Kim , Suk-Jin Yoon

We compile a holistic scenario for molecular cloud (MC) evolution and control of the star formation efficiency (SFE), and present a first set of numerical tests of it. A {\it lossy} compressible cascade can generate density fluctuations and…

Astrophysics · Physics 2009-11-07 E. Vazquez-Semadeni , J. Ballesteros-Paredes , R. S. Klessen

We perform numerical simulations of nonlinear MHD waves in a gravitationally stratified molecular cloud that is bounded by a hot and tenuous external medium. We study the relation between the strength of the turbulence and various global…

Astrophysics · Physics 2009-11-10 T. Kudoh , S. Basu

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…

Astrophysics · Physics 2007-05-23 Enrique Vazquez-Semadeni , Thierry Passot
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