2003/11/17 by A. Allen, F. H. Shu, Frank H. Shu +2 · 57 citations
Physics and Astronomy · #Ambipolar diffusion #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Classical mechanics #Geometry #Gravitation #Isothermal process #Magnetic field #Magnetic flux #Magnetohydrodynamics #Mechanics #Physics #Plane (geometry) #Plasma #Stellar, planetary, and galactic studies #Toroid #astro-ph
paper · pdf · doi:10.1086/379242
published in The Astrophysical Journal 599(1), 351-362 (IOP Publishing) · 26 pages, 8 figures. To appear in v599 n1 ApJ December 10, 2003 issue
arxiv created 2003/11/17 · openalex publication_date 2003/12/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study numerically the collapse of nonrotating self-gravitating magnetized singular isothermal toroids characterized by sound speed, a , and level of magnetic to thermal support, H 0 . In qualitative agreement with treatments by Galli & Shu and other workers, we find that the infalling material is deflected by the field lines toward the equatorial plane, creating a high-density flattened structure, a pseudodisk. The pseudodisk contracts dynamically in the radial direction, dragging the field lines and threading them into a highly pinched configuration that resembles a split monopole. The oppositely directed field lines across the midplane and the large implied stresses may play a role in how magnetic flux is lost in the actual situation in the presence of finite resistivity or ambipolar diffusion. The infall rate into the central regions is given to 5% uncertainty by the formula = (1 + H 0 ) a 3 / G , where G is the universal gravitational constant, anticipated by semianalytical studies of the self-similar gravitational collapses of the singular isothermal sphere and isopedically magnetized disks. The introduction of finite initial rotation results in a complex interplay between pseudodisk and true (Keplerian) disk formation that is examined in a companion paper.