Conditions for the formation of first-star binaries

Masahiro N. Machida, Kazuyuki Omukai, Tomoaki Matsumoto, Shu Ichiro Inutsuka

Research output: Contribution to journalArticlepeer-review

72 Citations (Scopus)


The fragmentation process of primordial-gas cores during prestellar collapse is studied using three-dimensional nested-grid hydrodynamics. Starting from the initial central number density of nc ∼ 103 cm-3, we follow the evolution of rotating spherical cores up to the stellar density nc ≃ 1022 cm-3. An initial condition of the cores is specified by three parameters: the ratios of the rotation and thermal energies to the gravitational energy ( β0 and α0, respectively), and the amplitude of the bar-mode density perturbation (AΦ). Cores with rotation β0 > 10-6 are found to fragment during the collapse. The fragmentation condition hardly depends on either the initial thermal energy α0 or amplitude of bar-mode perturbation AΦ. Since the critical rotation parameter for fragmentation is lower than that expected in first-star formation, binaries or multiples are also common for the first stars.

Original languageEnglish
Pages (from-to)813-827
Number of pages15
JournalAstrophysical Journal
Issue number2
Publication statusPublished - Apr 20 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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