Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation

By Matthew R. Bate. 2011

430 citations recorded by the source corpus.

We report the statistical properties of stars, brown dwarfs and multiple systems obtained from the largest radiation hydrodynamical simulation of star cluster formation to date that resolves masses down to the opacity limit for fragmentation (a few Jupiter masses). The initial conditions are identical to those of previous barotropic calculations published by Bate, but this time the calculation is performed using a realistic equation of state and radiation hydrodynamics. The calculation uses sink particles to model 183 stars and brown dwarfs, including 28 binaries and 12 higher-order multiple systems, the properties of which are compared to the results from observational surveys. We find that the radiation hydrodynamical/sink particle simulation reproduces many observed stellar properties very well. In particular, whereas using a barotropic equation of state produces more brown dwarfs than stars, the inclusion of radiative feedback results in a stellar mass function and a ratio of brown dwarfs to stars in good agreement with observations of Galactic star-forming regions. In addition, many of the other statistical properties of the stars and brown dwarfs are in reasonable agreement with observations, including multiplicity as a function of primary mass, the frequency of very low mass binaries, and general trends for the mass ratio and separation distributions of binaries. We also examine the velocity dispersion of the stars, the distributions of disc truncation radii due to dynamical interactions, and coplanarity of orbits and sink particle spins in multiple systems. Overall, the calculation produces a cluster of stars whose statistical properties are difficult to distinguish from observed systems, implying that gravity, hydrodynamics and radiative feedback are the primary ingredients for determining the origin of the statistical properties of low-mass stars.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/3d9107ee4c72d150bf6e1388c4e7049ecbb32640

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Citations in the corpus

Global hierarchical collapse in molecular clouds. Towards a comprehensive scenario (2019, background): “1 Myr, because they are often aimed at studying the details of the stellar products (multiplicity, IMF, brown dwarf production, etc.; e.g., Bate 2012; Kuznetsova et al. 2015), rather than at the evolution of the GMC-scale system, over timescales of a few tens of megayears, from their formation to…”
PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, background): “Large-scale hydrodynamical simulations of fragmenting molecular clouds by Bate (2009) and Bate (2012) produced brown dwarf companion frequencies with no discernible dependency on the primary host star mass.”
On the diversity and statistical properties of protostellar discs (2018, methodology): “The missing radiative feedback may have a small effect on the level of fragmentation, although because of the use of very small sink particles and the fact that only low-mass stars are produced, Bate 2012 demonstrated empirically that this effect is likely to be small.”
RADIATION-HYDRODYNAMIC SIMULATIONS OF THE FORMATION OF ORION-LIKE STAR CLUSTERS. II. THE INITIAL MASS FUNCTION FROM WINDS, TURBULENCE, AND RADIATION (2012, methodology): “…whether it be an imposed equation of state (e.g. Bate & Bonnell 2005; Jappsen et al. 2005) or the inclusion of radiative transfer, either without (Bate 2009b, 2012) or with (Krumholz et al. 2007a, 2010, 2011; Offner et al. 2009; Urban et al. 2010) the further step of including stellar radiation.”
Stellar Multiplicity (2013, background): “Numerical simulations including the effects of magnetic field and/or radiative feedback appear to match more closely observed multiplicity properties since these processes severely hinder fragmentation (e.g., Bate 2012, Hennebelle & Teyssier 2008).”
Gravitational Instabilities in Circumstellar Disks (2016, background): “Bate (2012) provides the largest statistical sample of simulated binary formation, which matches well with observations of the field.”
KINEMATIC AND SPATIAL SUBSTRUCTURE IN NGC 2264 (2015, background): “…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. 2006).”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, background): “…environments), and generate galactic chimneys and super-bubbles c© 0000 RAS, MNRAS 000, 000–000 that generate fountains and super-winds (e.g. Krumholz et al. 2007, 2011; Offner et al. 2009, 2011; Harper-Clark & Murray 2011; Bate 2012; Wise et al. 2012; Pawlik et al. 2013; Muratov et al. 2013).”
The Formation and Early Evolution of Low-Mass Stars and Brown Dwarfs (2012, background): “The trends in mass ratio and mean separation as a function of stellar mass are also qualitatively reproduced by Bate (2009, 2012).”
Galaxies on FIRE (Feedback In Realistic Environments): stellar feedback explains cosmologically inefficient star formation (2013, background): “…these have necessarily been restricted to very small systems, either single molecular clouds/star clusters (e.g. Krumholz et al. 2007, 2011; Offner et al. 2009, 2011; HarperClark & Murray 2011; Bate 2012), or the “first stars” (e.g. Wise et al. 2012; Pawlik et al. 2013; Muratov et al. 2013).”
FROM BINARIES TO MULTIPLES. II. HIERARCHICAL MULTIPLICITY OF F AND G DWARFS (2014, background): “Hydrodynamical simulations (Bate 2012) reveal a complex process of binary formation and early evolution that shapes the multiplicity statistics.”
The VAST Survey - III. The multiplicity of A-type stars within 75 pc (2013, background): “…of the MF of solar-type primaries is lower than the predictions emerging from the barotropic hydrodynamicl simulation (Bate 2009), and numericalN -body interactions (Sterzik & Durisen 2003; Hubber & Whitworth 2005), while being consistent with the radiation hydrodynamical simulation (Bate 2012).”
THE ASTRALUX LARGE M-DWARF MULTIPLICITY SURVEY (2012, background): “We also make the same comparison of a uniform and rising sample to the Bate (2012) sample of simulated star formation.”
THE VLA NASCENT DISK AND MULTIPLICITY SURVEY OF PERSEUS PROTOSTARS (VANDAM). II. MULTIPLICITY OF PROTOSTARS IN THE PERSEUS MOLECULAR CLOUD (2016, methodology): “…possible processes (and combinations thereof): (1) turbulent fragmentation of the molecular cloud (e.g., Padoan & Nordlund 2002; Offner et al. 2010; Bate 2012), (2) the thermal fragmentation of strongly perturbed, rotating, and infalling core (e.g., Inutsuka & Miyama 1992; Burkert & Bodenheimer…”
Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars (2016, background): “…the pre-MS phase via physical processes such as fragmentation, fission, competitive accretion, and/or mass transfer through Roche-lobe overflow (Bonnell & Bastien 1992; Clarke 1996; Kroupa 1995a; Bate & Bonnell 1997; Kratter & Matzner 2006; Kouwenhoven et al. 2009; Marks & Kroupa 2011; Bate 2012).”
STELLAR POPULATIONS IN THE CENTRAL 0.5 pc OF THE GALAXY. II. THE INITIAL MASS FUNCTION (2013, result): “Star formation theories do not yet predict an analytic functional form for the MF, CSF, and q distributions and how they vary with primary mass; however, simulations are beginning to produce distributions that are in rough agreement with observations (Bate 2012; Krumholz et al. 2012).”