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Measurements of the star formation efficiency (SFE) of giant molecular clouds (GMCs) in the Milky Way generally show a large scatter, which could be intrinsic or observational. We use magnetohydrodynamic simulations of GMCs (including…

Star formation on galactic scales is known to be a slow process, but whether it is slow on smaller scales is uncertain. We cross-correlate 5469 giant molecular clouds (GMCs) from a new all-sky catalog with 256 star forming complexes (SFCs)…

Astrophysics of Galaxies · Physics 2016-12-28 Eve J. Lee , Marc-Antoine Miville-Deschenes , Norman Murray

We summarize recent numerical results on the control of the star formation efficiency (SFE), addressing the effects of turbulence and the magnetic field strength. In closed-box numerical simulations, the effect of the turbulent Mach number…

Astrophysics · Physics 2009-11-11 Enrique Vazquez-Semadeni

The star formation efficiency (SFE) measures the proportion of molecular gas converted into stars, while the star formation rate (SFR) indicates the rate at which gas is transformed into stars. Here we propose such a model in the framework…

Astrophysics of Galaxies · Physics 2025-02-25 An-Xu Luo , Hong-Li Liu , Jin-Zeng Li

Giant molecular clouds (GMCs) are the sites of star formation and stellar feedback in galaxies. Their properties set the initial conditions for star formation and their lifecycles determine how feedback regulates galaxy evolution. In recent…

Astrophysics of Galaxies · Physics 2022-03-21 Mélanie Chevance , Mark R. Krumholz , Anna F. McLeod , Eve C. Ostriker , Erik W. Rosolowsky , Amiel Sternberg

Stars generally form faster than the ambipolar diffusion time, suggesting that several processes short circuit the delay and promote a rapid collapse. These processes are considered here, including turbulence compression in the outer parts…

Astrophysics · Physics 2009-11-13 Bruce G. Elmegreen

We test some ideas for star formation relations against data on local molecular clouds. On a cloud by cloud basis, the relation between the surface density of star formation rate and surface density of gas divided by a free-fall time,…

Astrophysics of Galaxies · Physics 2015-06-18 Neal J. Evans , Amanda Heiderman , Nalin Vutisalchavakul

We present a large suite of MHD simulations of turbulent, star-forming giant molecular clouds(GMCs) with stellar feedback, extending previous work by simulating 10 different random realizations for each point in the parameter space of cloud…

Observations that resolve nearby galaxies into individual regions across multiple phases of the gas-star formation-feedback ``matter cycle'' have provided a sharp new view of molecular clouds, star formation efficiencies, timescales for…

Astrophysics of Galaxies · Physics 2024-04-01 Eva Schinnerer , Adam K. Leroy

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

The relations between star formation and properties of molecular clouds are studied based on a sample of star forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of…

Solar and Stellar Astrophysics · Physics 2017-03-08 Nalin Vutisalchavakul , Neal J. Evans , Mark Heyer

We present an idealized, semi-empirical model for the evolution of gravitationally contracting molecular clouds (MCs) and their star formation rate (SFR) and efficiency (SFE). The model assumes that the instantaneous SFR is given by the…

Astrophysics of Galaxies · Physics 2015-05-28 Manuel Zamora-Aviles , Enrique Vázquez-Semadeni , Pedro Colín

We investigate the formation of stars within giant molecular clouds (GMCs) evolving in environments of different global magnetic field strength and large-scale dynamics. Building upon a series of magnetohydrodynamic (MHD) simulations of…

Astrophysics of Galaxies · Physics 2020-03-25 Benjamin Wu , Jonathan C. Tan , Duncan Christie , Fumitaka Nakamura

Star formation is inefficient. Recent advances in numerical simulations and theoretical models of molecular clouds show that the combined effects of interstellar turbulence, magnetic fields and stellar feedback can explain the low…

Solar and Stellar Astrophysics · Physics 2020-02-12 Christoph Federrath

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 examine the physical parameters that affect the accumulation of gas in molecular clouds to high column densities where the formation of stars takes place. In particular, we analyze the dense gas mass fraction (DGMF) in a set of…

Astrophysics of Galaxies · Physics 2015-06-15 Jouni Kainulainen , Christoph Federrath , Thomas Henning

We study giant molecular cloud (GMC) collisions and their ability to trigger star cluster formation. We further develop our three dimensional magnetized, turbulent, colliding GMC simulations by implementing star formation sub-grid models.…

Astrophysics of Galaxies · Physics 2017-06-14 Benjamin Wu , Jonathan C. Tan , Duncan Christie , Fumitaka Nakamura , Sven Van Loo , David Collins

We investigate how the dynamical state of molecular clouds relates to host galaxy environment, and how this impacts the star formation efficiency in the Milky Way and seven nearby galaxies. We compile measurements of molecular cloud and…

Astrophysics of Galaxies · Physics 2019-09-25 Andreas Schruba , J. M. Diederik Kruijssen , Adam K. Leroy

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,…

Astrophysics · Physics 2007-05-23 J. Ballesteros-Paredes , R. S. Klessen , M. -M. Mac Low , E. Vazquez-Semadeni

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…

Astrophysics · Physics 2015-06-24 Mark R. Krumholz