The effect of the dynamical state of clusters on gas expulsion and infant mortality

Goodwin, S. P.

doi:10.1007/s10509-009-0116-5

Cited by 73 publications

(101 citation statements)

References 29 publications

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“…The most common procedure is to start with a star cluster in a gas potential, whose depth relative to the potential produced by the stars is specified by the star formation efficiency. The stars themselves can be either smoothly distributed and in virial equilibrium with the gas (Tutukov 1978;Lada et al 1984;Goodwin 1997;Kroupa et (Chen & Ko 2009;Goodwin 16 It is critical to distinguish between and ff . The latter describes the instantaneous rate of conversion from gas to stars, while the former is the integrated fraction of the gas that is converted into stars over the entire lifetime of the star-forming system.…”

Section: Gas Removal 521 General Theorymentioning

confidence: 99%

The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function

2014

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Star formation lies at the center of a web of processes that drive cosmic evolution: generation of radiant energy, synthesis of elements, formation of planets, and development of life. Decades of observations have yielded a variety of empirical rules about how it operates, but at present we have no comprehensive, quantitative theory. In this review I discuss the current state of the field of star formation, focusing on three central questions: what controls the rate at which gas in a galaxy converts to stars? What determines how those stars are clustered, and what fraction of the stellar population ends up in gravitationally-bound structures? What determines the stellar initial mass function, and does it vary with star-forming environment? I use these three question as a lens to introduce the basics of star formation, beginning with a review of the observational phenomenology and the basic physical processes. I then review the status of current theories that attempt to solve each of the three problems, pointing out links between them and opportunities for theoretical and numerical work that crosses the scale between them. I conclude with a discussion of prospects for theoretical progress in the coming years.

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Section: Gas Removal 521 General Theorymentioning

confidence: 99%

The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function

2014

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“…Even if the cluster manages to survive for the 4 Myr of our simulations, shortly after this the most massive stars will become supernovae and the loss of the most bound portions of the cluster should destroy the cluster. Thus clusters can be destroyed dynamically without the need for gas expulsion (Goodwin & Bastian 2006;Goodwin 2009).…”

Section: Core Collapse?mentioning

confidence: 99%

The early dynamical evolution of cool, clumpy star clusters

Allison

Goodwin

Parker

et al. 2010

Monthly Notices of the Royal Astronomical Society

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Observations and theory both suggest that star clusters form sub-virial (cool) with highly sub-structured distributions. We perform a large ensemble of N-body simulations of moderate-sized (N=1000) cool, fractal clusters to investigate their early dynamical evolution. We find that cool, clumpy clusters dynamically mass segregate on a short timescale, that Trapezium-like massive higher-order multiples are commonly formed, and that massive stars are often ejected from clusters with velocities > 10 km/s (c.f. the average escape velocity of 2.5 km/s). The properties of clusters also change rapidly on very short timescales. Young clusters may also undergo core collapse events, in which a dense core containing massive stars is hardened due to energy losses to a halo of lower-mass stars. Such events can blow young clusters apart with no need for gas expulsion. The warmer and less substructured a cluster is initially, the less extreme its evolution.Comment: Accepted for publication in MNRAS; supplementary material can be downloaded at http://sgoodwin.staff.shef.ac.uk/all_plots.pdf.g

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“…Formally, the bound fraction F bound depends on the ‘effective’ star formation efficiency (eSFE, Verschueren 1990; Goodwin & Bastian 2006; Goodwin 2009), rather than on the local SFE. That is, F bound = F bound (eSFE, τ GExp /τ cross ).…”

Section: Core Mass–radius Relation and External Tidal Fieldmentioning

confidence: 99%

The puzzle of the cluster-forming core mass-radius relation and why it matters

Parmentier

Kroupa

2010

Monthly Notices of the Royal Astronomical Society

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We highlight how the mass–radius relation of cluster‐forming cores combined with an external tidal field can influence infant weight‐loss and disruption likelihood of clusters at the end of their violent relaxation, namely, when their dynamical response to the expulsion of their residual star‐forming gas is over. Specifically, building on the cluster N‐body model grid of Baumgardt & Kroupa (2007), we study how the relation between the bound fraction of stars staying in clusters at the end of violent relaxation and the cluster‐forming core mass is affected by the slope and normalization of the core mass–radius relation. Assuming mass‐independent star formation efficiency and gas‐expulsion time‐scale τGExp/τcross and a given external tidal field, it is found that constant surface density cores and constant radius cores have the potential to lead to the preferential removal of high‐ and low‐mass clusters, respectively. In contrast, constant volume density cores result in mass‐independent cluster infant weight‐loss, as suggested by some observations. These trends result from how core volume density and core mass scale with each other. Infant weight‐loss is quantified for cluster‐forming cores with number density , surface density Σcore≃ 0.5 g cm−2 or radius rcore= 0.3 pc. Our modelling includes predictions about the evolution of high‐mass cluster‐forming cores (say mcore > 105 M⊙), a regime not yet covered by the observations. We show how, for a given external tidal field, the core mass–radius diagram constitutes a straightforward diagnostic tool to assess whether the tidal field influences the fate of clusters after gas expulsion. An overview of various issues directly affected by the nature of the core mass–radius relation is presented. In relation to the tidal field impact, these are the evolution of the cluster mass function at young ages (i.e. over the first ≃30 Myr), and our ability to reconstruct the star formation history of galaxies from their cluster age distribution. Independently of the tidal field impact, the slope and/or normalization of the cluster‐forming core mass–radius relation also influences the mass–metallicity relation of old globular clusters predicted by self‐enrichment models, and the duration of cluster violent relaxation. Finally, we emphasize that observational mass–radius data sets of dense gas regions must be handled with caution as they may be the imprint of the molecular tracer used to map them, rather than reflecting cluster formation conditions.

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The effect of the dynamical state of clusters on gas expulsion and infant mortality

Cited by 73 publications

References 29 publications

The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function

The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function

The early dynamical evolution of cool, clumpy star clusters

The puzzle of the cluster-forming core mass-radius relation and why it matters

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