ANALYTICAL STAR FORMATION RATE FROM GRAVOTURBULENT FRAGMENTATION

By P. Hennebelle, G. Chabrier. 2011

184 citations recorded by the source corpus.

We present an analytical determination of the star formation rate (SFR) in molecular clouds, based on a time-dependent extension of our analytical theory of the stellar initial mass function. The theory yields SFRs in good agreement with observations, suggesting that turbulence is the dominant, initial process responsible for star formation. In contrast to previous SFR theories, the present one does not invoke an ad hoc density threshold for star formation; instead, the SFR continuously increases with gas density, naturally yielding two different characteristic regimes, thus two different slopes in the SFR versus gas density relationship, in agreement with observational determinations. Besides the complete SFR derivation, we also provide a simplified expression, which reproduces the complete calculations reasonably well and can easily be used for quick determinations of SFRs in cloud environments. A key property at the heart of both our complete and simplified theory is that the SFR involves a density-dependent dynamical time, characteristic of each collapsing (prestellar) overdense region in the cloud, instead of one single mean or critical freefall timescale. Unfortunately, the SFR also depends on some ill-determined parameters, such as the core-to-star mass conversion efficiency and the crossing timescale. Although we provide estimates for these parameters, their uncertainty hampers a precise quantitative determination of the SFR, within less than a factor of a few.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/d344a3a6e48a3c9b084112a77b3525b3551bff23

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Citations in the corpus

ON THE STAR FORMATION EFFICIENCY OF TURBULENT MAGNETIZED CLOUDS (2012, background): “…2009; Elmegreen 2011; Veltchev et al. 2011; Donkov et al. 2012; Parravano et al. 2012; Hopkins 2012c,a), the Kennicutt-Schmidt relation (Krumholz & McKee 2005; Tassis 2007), the SFE (Elmegreen 2008), and the SFR (Krumholz & McKee 2005; Padoan & Nordlund 2011; Hennebelle & Chabrier 2011, Paper I).”
THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS (2012, methodology): “…density scrit,HC is defined by requiring that the turbulent Jeans length λJ,turb at the critical density is a fraction ycut of the cloud scale L. Hennebelle & Chabrier (2011) do not provide an explicit physical interpretation of this choice, but a follow-up study is in preparation (P.…”
Star formation rates and efficiencies in the Galactic Centre (2017, background): “On the other hand, assuming that the free-fall time varies as a function of density, as suggested initially by Hennebelle & Chabrier (2011), requires the integral to be solved over the lognormal probability distribution.”
On the universality of supersonic turbulence (2013, background): “…Klessen 2004; McKee & Ostriker 2007), because it controls the rate of star formation triggered by gas compression in shocks (Krumholz & McKee 2005; Hennebelle & Chabrier 2011; Padoan & Nordlund 2011; Federrath & Klessen 2012), affects the star formation efficiency (Elmegreen 2008; Federrath &…”
Physical Processes in the Interstellar Medium (2014, background): “…likely to be gravitationally bound, since MJ ∝ n−1/2, and so the result of an increase in the Mach number of the turbulence will typically be an increase in the star formation rate of the gas (Krumholz & McKee, 2005; Padoan & Nordlund, 2011; Hennebelle & Chabrier, 2011; Federrath & Klessen, 2012).”
Global hierarchical collapse in molecular clouds. Towards a comprehensive scenario (2019, methodology): “The model, hereafter referred to as the ZV14 model, considers, similarly to other models of the SFR (Krumholz & McKee 2005; Hennebelle & Chabrier 2011; Padoan & Nordlund 2011; Federrath & Klessen 2012), that the turbulence generates a probability density distribution (PDF) of the density field,…”
Star Formation in the Milky Way and Nearby Galaxies (2012, background): “In a model that accounts for this, Hennebelle & Chabrier (2011) reproduce at some level the observations of surface density thresholds for efficient star formation observed in nearby clouds (Lada et al. 2010; Heiderman et al. 2010).”
Turbulent molecular clouds (2012, methodology): “Various authors (namely Krumholz & McKee 2005, Padoan & Nordlund 2011, Hennebelle & Chabrier 2011) have been recently proposing analytical theories that predict the star–formation rate within molecular clouds.”
Dense gas in the Galactic central molecular zone is warm and heated by turbulence (2015, background): “…of star formation now invoke turbulence to provide the core fragmentation spectrum, so the thermal Jeans scale is less relevant for setting core masses (Krumholz & McKee 2005; Hennebelle & Chabrier 2011; Padoan & Nordlund 2011; Federrath & Klessen 2012; Hennebelle & Chabrier 2013; Hopkins 2013).”
The Stellar IMF, Core Mass Function, & The Last-Crossing Distribution (2012, unknown): “…given by the Jeans condition for thermal plus turbulent velocities, this argument reproduces all of the key features of the observed CMF and stellar IMF (for extensions of this calculation allowing for different gas properties and , see Hennebelle & Chabrier 2009, 2011; Chabrier & Hennebelle 2011).”
ON THE INTERPLAY BETWEEN STAR FORMATION AND FEEDBACK IN GALAXY FORMATION SIMULATIONS (2014, background): “…of star formation in super sonic turbulence, aimed at understanding what sets the star formation efficiency per free-fall time and its evolution in GMCs, has been carried out recently (see e.g. Krumholz & McKee 2005; Padoan & Nordlund 2011; Vázquez-Semadeni et al. 2011; Hennebelle & Chabrier 2011).”
STAR FORMATION RELATIONS IN NEARBY MOLECULAR CLOUDS (2014, background): “Our results suggest that the free-fall time calculated from large-scale mean densities is not a useful parameter for predicting star formation rates, but tff calculated more locally may be relevant, as suggested by Hennebelle & Chabrier (2011).”
Discovery of a warm, dusty giant planet around HIP 65426 (2017, methodology): “Finally, the formation of an extreme mass-ratio binary by gravo-turbulent fragmentation (Hennebelle & Chabrier 2011) cannot be excluded.”
Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies (2017, unknown): “…recipe of Rasera & Teyssier (2006) is that the star formation efficiency is not a constant, but rather derived from the local properties of the gas (Hennebelle & Chabrier 2011; Federrath & Klessen 2012): ∝ e 3 8σ 2 s ©«1 + erf ©« σ2s − scrit√ 2σ2s ª®®¬ ª®®¬ , (2) where σs = σs(σgas, cs)…”
A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from the Herschel Gould Belt survey (2015, methodology): “…turbulence and that clouds typically convert ff ∼ 1% of their molecular gas mass into stars per (local) free-fall time (e.g., Padoan & Nordlund 2011; Hennebelle & Chabrier 2011; Krumholz et al. 2012 – see also Federrath & Klessen 2012 and Padoan et al. 2014, for overviews and comparisons of the…”