Stellar collisions and the interior structure of blue stragglers

James C. Lombardi*, Jessica S. Warren, Frederic A. Rasio, Alison Sills, Aaron R. Warren

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

115 Scopus citations


Collisions of main-sequence stars occur frequently in dense star clusters. In open and globular clusters, these collisions produce merger remnants that may be observed as blue stragglers. Detailed theoretical models of this process require lengthy hydrodynamic computations in three dimensions. However, a less computationally expensive approach, which we present here, is to approximate the merger process (including shock heating, hydrodynamic mixing, mass ejection, and angular momentum transfer) with simple algorithms based on conservation laws and a basic qualitative understanding of the hydrodynamics. These algorithms have been fine-tuned through comparisons with the results of our previous hydrodynamic simulations. We find that the thermodynamic and chemical composition profiles of our simple models agree very well with those from recent SPH (smoothed particle hydrodynamics) calculations of stellar collisions, and the subsequent stellar evolution of our simple models also matches closely that of the more accurate hydrodynamic models. Our algorithms have been implemented in an easy-to-use software package, which we are making publicly available. This software could be used in combination with realistic dynamical simulations of star clusters that must take into account stellar collisions.

Original languageEnglish (US)
Pages (from-to)939-953
Number of pages15
JournalAstrophysical Journal
Issue number2 I
StatePublished - Apr 1 2002


  • Blue stragglers
  • Globular clusters: general
  • Hydrodynamics
  • Stars: evolution
  • Stars: interiors
  • Stellar dynamics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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