Magnetic molecular clouds - Indirect evidence for magnetic support and ambipolar diffusion

Abstract

view Abstract Citations (238) References (61) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Magnetic Molecular Clouds: Indirect Evidence for Magnetic Support and Ambipolar Diffusion Myers, P. C. ; Goodman, A. A. Abstract Over 120 measurements of molecular cloud size R, velocity dispersion σ, and density n are compiled to investigate the well-known relations σ ∝ R1/2, n ∝ R-1, and GM/R ≈ σ2. For cloud sizes from 0.1 to 100 pc, a crude virial equilibrium model of thermal and magnetic support against gravity fits the observed trends, provided the one free parameter, magnetic field strength, is 15 - 40 μG. This model is consistent with observations of low-mass cloud cores if their ratio of magnetic to gravitational energy, or their ratio of flux to mass, is smaller than in larger clouds - a situation expected in models of core formation by ambipolar diffusion. Furthermore, for typical equilibrium field strengths, the time scale for ambipolar diffusion is shortest when the cloud size is about 0.1 pc, as is typical of low-mass cores. Publication: The Astrophysical Journal Pub Date: June 1988 DOI: 10.1086/166385 Bibcode: 1988ApJ...329..392M Keywords: Ambipolar Diffusion; Gravitational Fields; Interstellar Magnetic Fields; Molecular Clouds; Centimeter Waves; Field Strength; Magnetohydrodynamics; Molecular Spectra; Virial Theorem; Zeeman Effect; Astrophysics; HYDROMAGNETICS; INTERSTELLAR: MAGNETIC FIELDS; INTERSTELLAR: MOLECULES full text sources ADS |