Stellar collisions during binary–binary and binary–single star interactions

By John Fregeau, Pokman Cheung, S. P. Portegies Zwart, F. Rasio. 2004

268 citations recorded by the source corpus.

Physical collisions between stars occur frequently in dense star clusters, either via close encounters between two single stars, or during strong dynamical interactions involving binary stars. Here we study stellar collisions that occur during binary-single and binary-binary interactions, by performing numerical scattering experiments. Our results include cross-sections, branching ratios and sample distributions of parameters for various outcomes. For interactions of hard binaries containing main-sequence stars, we find that the normalized cross-section for at least one collision to occur (between any two of the four stars involved) is essentially unity, and that the probability of collisions involving more than two stars is significant. Hydrodynamic calculations have shown that the effective radius of a collision product can be 2-30 times larger than the normal main-sequence radius for a star of the same total mass. We study the effect of this expansion, and find that it increases the probability of further collisions considerably. We discuss these results in the context of recent observations of blue stragglers in globular clusters with masses exceeding twice the main-sequence turn-off mass. We also present FEWBODY, a new, freely available numerical toolkit for simulating small-N gravitational dynamics that is particularly suited to performing scattering experiments.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/b015801d17b8107ae58fe419e6020915ebf47962

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Citations in the corpus

Binary Mergers and Growth of Black Holes in Dense Star Clusters (2005, methodology): “Each dynamical binary interaction is followed using Fewbody, a numerical toolkit for simulating small-N gravitational dynamics that provides automatic calculation termination and classification of outcomes (for a detailed description see Fregeau et al. 2004).”
Eccentric Black Hole Mergers in Dense Star Clusters: The Role of Binary–Binary Encounters (2018, methodology): “…of the outer component’s orbit relative to the orbital plane of the inner binary and once we again use the top-down notation (for example, a11 is the SMA of the inner binary in the triple, m12 is the total mass of the inner binary, and m11 is the mass of the tertiary, see Fregeau et al. 2004).”
DYNAMICAL FORMATION OF THE GW150914 BINARY BLACK HOLE (2016, methodology): “Strong three-body and four-body gravitational scattering encounters, computed by direct summation of Newtonian gravity with the Fewbody integrator (Fregeau et al. 2004); and 3.”
The evolution of binary fractions in globular clusters (2005, methodology): “Note the peak in evolutionary disruptionsat t ∼ 107–108 yr, which is due to supernovae. ments show that, for hard binaries containing main-sequence stars most encounters will lead to a physical collision (Fregeau et al. 2004).”
Rapid Eccentricity Oscillations and the Mergers of Compact Objects in Hierarchical Triples (2013, methodology): “We numerically evolve triple systems with the open source Fewbody suite (Fregeau et al. 2004).”
Formation and evolution of compact binaries in globular clusters – II. Binaries with neutron stars (2007, background): “In addition, when a binary encounter involves a very tight binary, which would be likely to start MT soon even in the caseof post-exchange expansion, a physical collision during the binary encounter is more likely than a simple exchange (Fregeau et al.2004).”
Young Massive Star Clusters (2010, background): “It is quite likely that the third star will also be engulfed in the collision product (Fregeau et al. 2004).”
MOCCA-SURVEY Database - I. Coalescing binary black holes originating from globular clusters (2016, methodology): “…Pols, & Tout (2000) and Hurley, Tout, & Pols (2002) (bse code), (2) direct integration procedures for small N sub-systems using the fewbody code (Fregeau et al. 2004), and (3) a realistic treatment of escape processes in tidally limited clusters based on Fukushige & Heggie (2000). mocca has…”
The Birth of High-Mass Stars: Accretion and/or Mergers? (2005, background): “…a main-sequence star with the same mass. Numerical models of stellar collisions leading to the formation of blue stragglers in globular clusters (Lombardi et al. 2002, 2003; Fregeau et al. 2004) indicate that merger products have radii up to 30 times larger than an equivalent main sequence star.”
ACCELERATING COMPACT OBJECT MERGERS IN TRIPLE SYSTEMS WITH THE KOZAI RESONANCE: A MECHANISM FOR “PROMPT” TYPE Ia SUPERNOVAE, GAMMA-RAY BURSTS, AND OTHER EXOTICA (2010, background): “…mechanism for the formation of triple systems that lead to Kozai-induced mass transfer has been studied by Ivanova (2008) and Ivanova et al. (2008,2010), and has been found to be important for producing the observed X-ray binary populations of globular clusters (see also Fregeau et al. 2004, 2009).”
Intermediate mass black holes in AGN discs – I. Production and growth (2012, background): “However, if there is even one in the initial AGN disk, it will have the largest collisional cross-section of any disk NCO and should undergo the largest number of interactions (e.g. Portegies-Zwart et al. 1999; Fregeau et al. 2004).”
The dragon simulations: globular cluster evolution with a million stars (2016, background): “MOCCA is a heterogeneous code, composed of independent modules including single and binary star evolution (Hurley, Pols, & Tout 2000; Hurley, Tout, & Pols 2002), few-body scattering (Fregeau et al. 2004) and escape processes in tidally limited clusters (Fukushige & Heggie 2000).”
MOCCA code for star cluster simulations – IV. A new scenario for intermediate mass black hole formation in globular clusters (2015, methodology): “…Tout, & Pols (2002) (from now on we will refer to both codes together as BSE), (2) direct integration procedures for mall N sub-systems using the Fewbody code (Fregeau et al. 2004), and (3) a realistic treatment of escape processes in tidally limited clusters based on Fukushige & Heggie (2000).”
THE FORMATION OF ECCENTRIC COMPACT BINARY INSPIRALS AND THE ROLE OF GRAVITATIONAL WAVE EMISSION IN BINARY–SINGLE STELLAR ENCOUNTERS (2013, background): “Binary-single state Following Fregeau et al. (2004) we state that the three interacting objects are in a binary-single state if the binary objects are bound to each other and the tidal force from the single at the binary’s apocenter (Ftid) is smaller than the relative force at apocenter (Frel) by…”
Modeling Dense Star Clusters in the Milky Way and Beyond with the CMC Cluster Catalog (2019, methodology): “Such collisions can occur through single–single encounters, as well as during binary-mediated strong encounters that are integrated by Fewbody.”