Non-stationary Magnetic Microstructures in Stellar Thin Accretion Discs

Abstract

We examine the morphology of magnetic structures in thin plasma accretion discs, generalizing a stationary ideal MHD model to the time-dependent visco-resistive case. Our analysis deals with small scale perturbations to a central dipole-like magnetic field, which give rise -- as in the ideal case -- to the periodic modulation of magnetic flux surfaces along the radial direction, corresponding to the formation of a toroidal current channels sequence. These microstructures suffer an exponential damping in time because of the non-zero resistivity coefficient, allowing us to define a configuration lifetime which mainly depends on the midplane temperature and on the length scale of the structure itself. By means of this lifetime we show that the microstructures can exist within the inner region of stellar discs in a precise range of temperatures, and that their duration is consistent with local transient processes (minutes to hours).

14 text pages, 5 figures, to be published on PRE

References in corpus (5)

• MHD simulations of jet acceleration from Keplerian accretion disks: the effects of disk resistivity
• Advection/Diffusion of Large-Scale B-Field in Accretion Disks
• Crystalline Structure of Accretion Disks: Features of the Global Model
• Inconsistency in the Standard Model for Thin Accretion Disks
• Viscoresistive MHD Configurations of Plasma in Accretion Disks

Cited by in corpus (5)

• Study of MRI in stratified viscous plasma configuration
• Behavior of thin disk crystalline morphology in the presence of corrections to ideal magnetohydrodynamics
• Plasma Phenomenology in Astrophysical Systems: Radio-Sources and Jets
• General features of the linear crystalline morphology of accretion disks
• Contribution to the angular momentum transport paradigm for accretion disks