A multiphysics and multiscale software environment for modeling astrophysical systems     

Simon Portegies Zwart  Steve McMillan  Stefan Harfst  Derek Groen  Michiko Fujii  Breanndán Ó Nualláin  Evert Glebbeek  Douglas Heggie  James Lombardi  Piet Hut  Vangelis Angelou  Sambaran Banerjee  Houria Belkus  Tassos Fragos  John Fregeau  Evghenii Gaburov  Rob Izzard  Mario Jurić  Stephen Justham  Andrea Sottoriva  Marcel Zemp 《New Astronomy》2009,14(4):369-378

We present MUSE, a software framework for combining existing computational tools for different astrophysical domains into a single multiphysics, multiscale application. MUSE facilitates the coupling of existing codes written in different languages by providing inter-language tools and by specifying an interface between each module and the framework that represents a balance between generality and computational efficiency. This approach allows scientists to use combinations of codes to solve highly coupled problems without the need to write new codes for other domains or significantly alter their existing codes. MUSE currently incorporates the domains of stellar dynamics, stellar evolution and stellar hydrodynamics for studying generalized stellar systems. We have now reached a “Noah’s Ark” milestone, with (at least) two available numerical solvers for each domain. MUSE can treat multiscale and multiphysics systems in which the time- and size-scales are well separated, like simulating the evolution of planetary systems, small stellar associations, dense stellar clusters, galaxies and galactic nuclei. In this paper we describe three examples calculated using MUSE: the merger of two galaxies, the merger of two evolving stars, and a hybrid N-body simulation. In addition, we demonstrate an implementation of MUSE on a distributed computer which may also include special-purpose hardware, such as GRAPEs or GPUs, to accelerate computations. The current MUSE code base is publicly available as open source at http://muse.li.  相似文献   

SAPPORO: A way to turn your graphics cards into a GRAPE-6     

Evghenii Gaburov  Stefan Harfst  Simon Portegies Zwart 《New Astronomy》2009,14(7):630-637

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Common envelope evolution: where we stand and how we can move forward     

N. Ivanova  S. Justham  X. Chen  O. De Marco  C. L. Fryer  E. Gaburov  H. Ge  E. Glebbeek  Z. Han  X.-D. Li  G. Lu  T. Marsh  P. Podsiadlowski  A. Potter  N. Soker  R. Taam  T. M. Tauris  E. P. J. van den Heuvel  R. F. Webbink 《Astronomy and Astrophysics Review》2013,21(1):1-73

This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas of consensus and disagreement, and stress ideas which should point the way forward for progress in this important but long-standing and largely unconquered problem. Unusually for CEE-related work, we mostly try to avoid relying on results from population synthesis or observations, in order to avoid potentially being misled by previous misunderstandings. As far as possible we debate all the relevant issues starting from physics alone, all the way from the evolution of the binary system immediately before CEE begins to the processes which might occur just after the ejection of the envelope. In particular, we include extensive discussion about the energy sources and sinks operating in CEE, and hence examine the foundations of the standard energy formalism. Special attention is also given to comparing the results of hydrodynamic simulations from different groups and to discussing the potential effect of initial conditions on the differences in the outcomes. We compare current numerical techniques for the problem of CEE and also whether more appropriate tools could and should be produced (including new formulations of computational hydrodynamics, and attempts to include 3D processes within 1D codes). Finally we explore new ways to link CEE with observations. We compare previous simulations of CEE to the recent outburst from V1309 Sco, and discuss to what extent post-common-envelope binaries and nebulae can provide information, e.g. from binary eccentricities, which is not currently being fully exploited.  相似文献   

On the onset of runaway stellar collisions in dense star clusters – I. Dynamics of the first collision     

E. Gaburov  A. Gualandris  S. Portegies Zwart 《Monthly notices of the Royal Astronomical Society》2008,384(1):376-385

We study the circumstances under which first collisions occur in young and dense star clusters. The initial conditions for our direct N -body simulations are chosen such that the clusters experience core collapse within a few million years, before the most massive stars have left the main sequence. It turns out that the first collision is typically driven by the most massive stars in the cluster. Upon arrival in the cluster core, by dynamical friction, massive stars tend to form binaries. The enhanced cross-section of the binary compared to a single star causes other stars to engage the binary. A collision between one of the binary components and the incoming third star is then mediated by the encounters between the binary and other cluster members. Due to the geometry of the binary–single star engagement the relative velocity at the moment of impact is substantially different than in a two-body encounter. This may have profound consequences for the further evolution of the collision product.  相似文献