The nonisothermal stage of magnetic star formation. I. Formulation of the problem and method of solution

Matthew W. Kunz, Telemachos Ch Mouschovias

Research output: Contribution to journalArticle

Abstract

We formulate the problem of the formation and subsequent evolution of fragments (or cores) in magnetically supported, self-gravitating molecular clouds in two spatial dimensions. The six-fluid (neutrals, electrons, molecular and atomic ions, positively charged, negatively charged, and neutral grains) physical system is governed by the radiation, nonideal magnetohydrodynamic equations. The magnetic flux is not assumed to be frozen in any of the charged species. Its evolution is determined by a newly derived generalized Ohm's law, which accounts for the contributions of both elastic and inelastic collisions to ambipolar diffusion and Ohmic dissipation. The species abundances are calculated using an extensive chemical-equilibrium network. Both MRN and uniform grain size distributions are considered. The thermal evolution of the protostellar core and its effect on the dynamics are followed by employing the gray flux-limited diffusion approximation. Realistic temperature-dependent grain opacities are used that account for a variety of grain compositions. We have augmented the publicly available Zeus-MP code to take into consideration all these effects and have modified several of its algorithms to improve convergence, accuracy, and efficiency. Results of magnetic star formation simulations that accurately track the evolution of a protostellar fragment from a density ≃103 cm-3 to a density ≃10 15 cm-3, while rigorously accounting for both nonideal MHD processes and radiative transfer, are presented in a separate paper.

Original languageEnglish (US)
Pages (from-to)1895-1911
Number of pages17
JournalAstrophysical Journal
Volume693
Issue number2
DOIs
StatePublished - Mar 10 2009

Keywords

  • ISM: clouds
  • MHD
  • dust, extinction
  • magnetic fields
  • radiative transfer
  • stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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