2001/10/30 by Philip J. Armitage · 2 citations
Physics and Astronomy · #Accretion (finance) #Accretion disc #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Boundary (topology) #Boundary layer #Dissipation #Hydrostatic equilibrium #Magnetic field #Magnetohydrodynamic drive #Magnetohydrodynamics #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2002.05152.x
published as Mon.Not.Roy.Astron.Soc. 330 (2002) 895 · MNRAS, in press. Movies from the simulations are available at http://star-www.st-and.ac.uk/~pja3/movies.html
arxiv created 2001/10/30 · openalex publication_date 2002/03/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We use three-dimensional magnetohydrodynamic simulations to study the structure of the boundary layer between an accretion disc and a non-rotating, unmagnetized star. Under the assumption that cooling is efficient, we obtain a narrow but highly variable transition region in which the radial velocity is only a small fraction of the sound speed. A large fraction of the energy dissipation occurs in high-density gas adjacent to the hydrostatic stellar envelope, and may therefore be reprocessed and largely hidden from view of the observer. As suggested by Pringle, the magnetic field energy in the boundary layer is strongly amplified by shear, and exceeds that in the disc by an order of magnitude. These fields may play a role in generating the magnetic activity, X-ray emission and outflows in disc systems where the accretion rate is high enough to overwhelm the stellar magnetosphere.