The hierarchical formation of a stellar cluster

By Ian A. Bonnell, Matthew R. Bate, S. Vine. 2003

325 citations recorded by the source corpus.

Recent surveys of star-forming regions have shown that most stars, and probably all massive stars, are born in dense stellar clusters. The mechanism by which a molecular cloud fragments to form several hundred to thousands of individual stars has remained elusive. Here, we use a numerical simulation to follow the fragmentation of a turbulent molecular cloud, and the subsequent formation and early evolution of a stellar cluster containing more than 400 stars. We show that the stellar cluster forms through the hierarchical fragmentation of a turbulent molecular cloud. This leads to the formation of many small subclusters, which interact and merge to form the final stellar cluster. The hierarchical nature of the cluster formation has serious implications in terms of the properties of the new-born stars. The higher number-density of stars in subclusters, compared to a more uniform distribution arising from a monolithic formation, results in closer and more frequent dynamical interactions. Such close interactions can truncate circumstellar discs, harden existing binaries and potentially liberate a population of planets. We estimate that at least one-third of all stars, and most massive stars, suffer such disruptive interactions.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/62441d56bf46c21fd65c2cac52fc72dc1f1886d5

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Citations in the corpus

The maximum stellar mass, star-cluster formation and composite stellar populations (2005, background): “The result of a cluster formation simulation by Bonnell et al. (2003) is shown as a large triangle.”
The dynamical state of stellar structure in star‐forming regions (2011, methodology): “In this work, we analyse the hydrodynamical/N -body simulations of Bonnell et al. (2003) and Bonnell et al. (2008), extendingthe analysis of Maschberger et al. (2010) and Maschberger & Clarke (2011).”
Long-baseline interferometric multiplicity survey of the Sco-Cen OB association (2013, background): “Models have suggested that disruptive interactions can shape the formation of high-mass stars in dense clusters (Bonnell et al. 2003), but ejection in Sco-Cen is much less likely because OB associations are in general sparse environments.”
Slow Star Formation in Dense Gas: Evidence and Implications (2006, methodology): “At the other extreme, Bonnell et al. (2003) argue that star clusters form from gas clumps at densities of 5 ; 104 cm 3 that undergo a free-fall collapse in which at least 30% of their mass is converted into stars (Kroupa et al. 2001), so star formation should be rapid at this density or higher.”
THE EFFECTS OF RADIATIVE TRANSFER ON LOW-MASS STAR FORMATION (2009, background): “…simulations of molecular clouds frequently assume constant gas temperature, a convenient approximation for investigations of gas-dynamics, turbulence, and gravitational collapse (Gammie et al. 2003; Bonnell et al. 2003; Li et al. 2004; Tilley & Pudritz 2004; Vázquez-Semadeni et al. 2008).”
Interstellar Turbulence I: Observations and Processes (2004, methodology): “Self-gravitating models illustrate the process in detail (Bonnell et al. 1997, 2003; Klessen, Burkert & Bate 1998; Klessen & Burkert 2000; Klessen, Heitsch & Mac Low 2000), including magnetic fields (Heitsch, Mac Low & Klessen 2001; Bate, Bonnell & Bromm 2003; Li et al. 2003).”
Massive star formation: nurture, not nature (2004, background): “One of the major results of the simulation reported in Bonnell et al. (2003) is that the cluster formation process naturally results in a distribution of stellar masses from 0.1 to ≈ 27 M⊙, with a median mass of ≈ 0.43 M⊙, and that agrees broadly with observed initial mass functions.”
DYNAMICAL MASS SEGREGATION ON A VERY SHORT TIMESCALE (2009, background): “In hydrodynamic simulations of cluster formation starting from dynamically hot (globally unbound) gas the stars that form also appear to have subvirial motions (see e.g. Bate et al. 2003; Bonnell et al. 2003).”
Kinematics in Young Star Clusters and Associations with Gaia DR2 (2018, background): “…studies are: “monolithic” cluster formation, in which a young star cluster is born in a single molecular cloud core, and “hierarchical” cluster formation, in which larger clusters are built via the accumulation of smaller subclusters (Elmegreen 2000; Bonnell et al. 2003; Banerjee & Kroupa 2015).”
Stellar, brown dwarf and multiple star properties from hydrodynamical simulations of star cluster formation (2008, unknown): “Such hierarchical build-up of a stellar cluster was previously highlighted in the lower-resolution simulation of a 1000 M cloud performed by Bonnell et al. (2003).”
KINEMATIC AND SPATIAL SUBSTRUCTURE IN NGC 2264 (2015, background): “…cluster formation theories are generally comprised of two classes: highly dynamic, non-equilibrium models that form within a crossing time (e.g., Bonnell et al. 2003; Bate 2012) and quasiequilibrium and/or slow contraction scenarios that require several crossing times to form (e.g., Tan et al.…”
The Birth of High-Mass Stars: Accretion and/or Mergers? (2005, background): “However, as shown by Bonnell et al. (2003), gravitational collapse of a fragmenting core with an initial density of n(H2) = 10 5 cm−3 can lead to stellar densities of 106 to 108 stars per cubic pc for a brief period.”
MODELING COLLAPSE AND ACCRETION IN TURBULENT GAS CLOUDS: IMPLEMENTATION AND COMPARISON OF SINK PARTICLES IN AMR AND SPH (2010, background): “Typically, initial conditions are set up with roughly equal kinetic and gravitational energies, Ekin ≈ Egrav (e.g., Bate et al. 2003; Bonnell et al. 2003).”
Star formation through gravitational collapse and competitive accretion (2006, methodology): “Similar central condensations are produced in simulations of turbulent fragmentation and cluster formation (Bonnell et al. 2003).”
A SPITZER SURVEY OF YOUNG STELLAR CLUSTERS WITHIN ONE KILOPARSEC OF THE SUN: CLUSTER CORE EXTRACTION AND BASIC STRUCTURAL ANALYSIS (2009, methodology): “…numerical simulations are now being used to examine these processes in detail (e.g., Klessen & Burkert 2000; Klessen et al. 2000; Bate et al. 2003; Bonnell et al. 2003; Gammie et al. 2003; Li et al. 2004); however, the predictions of these simulations are difficult to verify by observations.”
Astrophysical smooth particle hydrodynamics (2009, methodology): “For the various approaches we refer to the literature (Navarro and White, 1993; Mihos and Hernquist, 1994; Bate et al., 1995, 2003; Gerritsen and Icke, 1997; Sommer-Larsen et al., 1999; Springel, 2000, 2005; Springel et al., 2001; Thacker and Couchman, 2000; Scannapieco et al., 2001; Thacker et al.,”