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We present the results of a numerical study designed to address the question of whether there is a column density threshold for star formation within molecular clouds. We have simulated a large number of different clouds, with volume and…

Astrophysics of Galaxies · Physics 2015-06-16 Paul C. Clark , Simon C. O. Glover

(Abridged) Aims & Methods. A two-dimensional, semi-analytical model is presented that follows, for the first time, the chemical evolution from a collapsing molecular cloud (a pre-stellar core) to a protostar and circumstellar disk. The…

Solar and Stellar Astrophysics · Physics 2009-11-13 R. Visser , E. F. van Dishoeck , S. D. Doty , C. P. Dullemond

We study the baryonic, chemical and dynamical properties of a significantly large sample of early proto-galaxies in the first 500 Myr of the Universe (redshift z>9), obtained from high-resolution numerical, N-body, hydrodynamical, chemistry…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Veronica Biffi , Umberto Maio

We describe a phenomenological model for molecular hydrogen formation suited for applications in galaxy formation simulations, which includes on-equilibrium formation of molecular hydrogen on dust and approximate treatment of both its…

Astrophysics · Physics 2010-12-28 Nickolay Y. Gnedin , Konstantinos Tassis , Andrey V. Kravtsov

[Abridged] Do some environments favor efficient conversion of molecular gas into stars? To answer this, we need to be able to estimate the H2 mass. Traditionally, this is done using CO and a few assumptions but the Herschel observations in…

We discuss molecular cloud formation by large-scale supersonic compressions in the diffuse warm neutral medium (WNM). Initially, a shocked layer forms, and within it, a thin cold layer. An analytical model and high-resolution 1D simulations…

Context. Low-mass star-forming cores differ from their surrounding molecular cloud in turbulence, shape, and density structure. Aims. We aim to understand how dense cores form out of the less dense cloud material by studying the connection…

Astrophysics of Galaxies · Physics 2015-05-28 A. Hacar , M. Tafalla

Star formation in strongly self-gravitating cloud cores should be similar at all redshifts, forming single or multiple stars with a range of masses determined by local magneto-hydrodynamics and gravity. The formation processes for these…

Astrophysics of Galaxies · Physics 2017-01-11 Bruce G. Elmegreen

Star formation is intimately linked to the dynamical evolution of molecular clouds. Turbulent fragmentation determines where and when protostellar cores form, and how they contract and grow in mass via accretion from the surrounding cloud…

Astrophysics · Physics 2007-05-23 Ralf Klessen

We report the first evidence for high-mass star formation triggered by collisions of molecular clouds in M33. Using the Atacama Large Millimeter/submillimeter Array, we spatially resolved filamentary structures of giant molecular cloud 37…

Star formation occurs within dusty molecular clouds that are then disrupted by stellar feedback. However, the timing and physical mechanisms that govern the transition from deeply embedded to exposed stars remain uncertain. Using the…

High-mass stars form within star clusters from dense, molecular regions, but is the process of cluster formation slow and hydrostatic or quick and dynamic? We link the physical properties of high-mass star-forming regions with their…

Astrophysics of Galaxies · Physics 2017-02-09 Cara Battersby , John Bally , Brian Svoboda

We investigate the formation of star clusters in an unbound GMC, where the supporting kinetic energy is twice as large as the cloud's self-gravity. This cloud manages to form a series of star clusters and disperse, all within roughly 2…

Astrophysics · Physics 2014-10-13 Paul C. Clark , Ian A. Bonnell , Hans Zinnecker , Matthew R. Bate

We analyse extinction maps of nearby Giant Molecular Clouds to forge a link between driving processes of turbulence and modes of star formation. Our investigation focuses on cloud structure in the column density range above the self…

Astrophysics of Galaxies · Physics 2015-05-28 J. Rowles , D. Froebrich

We present a new model to describe the star formation process in galaxies, which includes the description of the different gas phases -- molecular, atomic, and ionized -- together with its metal content. The model, which will be coupled to…

Astrophysics of Galaxies · Physics 2025-08-14 Ezequiel Lozano , Cecilia Scannapieco , Sebastian E. Nuza

We present a numerical study of the evolution of molecular clouds, from their formation by converging flows in the warm ISM, to their destruction by the ionizing feedback of the massive stars they form. We improve with respect to our…

Astrophysics of Galaxies · Physics 2015-06-15 Pedro Colin , Enrique Vazquez-Semadeni , Gilberto C. Gomez

Star formation in a filamentary infrared dark cloud (IRDC) is simulated over a dynamic range of 4.2 pc to 28 au for a period of $3.5\times 10^5$ yr, including magnetic fields and both radiative and outflow feedback from the protostars. At…

Astrophysics of Galaxies · Physics 2017-12-06 Pak Shing Li , Richard I. Klein , Christopher F. McKee

Molecular clouds are the cold regions of the Milky Way where stars form. They are enriched by rather complex molecules. Many of these molecules are believed to be synthesized on the icy surfaces of the interstellar submicron-sized dust…

Astrophysics of Galaxies · Physics 2020-07-08 Stefano Pantaleone , Joan Enrique-Romero , Cecilia Ceccarelli , Piero Ugliengo , Nadia Balucani , Albert Rimola

Stars and star clusters form by gravoturbulent fragmentation of interstellar gas clouds. The supersonic turbulence ubiquitously observed in Galactic molecular gas generates strong density fluctuations with gravity taking over in the densest…

Astrophysics of Galaxies · Physics 2015-05-30 Ralf S. Klessen

Methods: The microscopic equations of H2-formation and protonation are integrated numerically over time in such a manner that the overall structures evolve self-consistently under benign conditions. Results: The equilibrium H2 formation…

Astrophysics of Galaxies · Physics 2009-11-13 H. S. Liszt
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