منابع مشابه
The Standard - Accretion Disk
We consider the classic MHD turbulent dynamo operating in a thin, Keplerian accretion disk powered by turbulent viscous stress. The character of the turbulence is encapsulated into two constant parameters: the Shakura-Sunyaev dimensionless viscosity, SS , and the Coriolis number, = 2 corr. The dependence of the total electromotive force on SS and is derived and the dynamo-generated magnetic eld...
متن کاملGalactic and Accretion Disk Dynamos
Dynamos in astrophysical disks are usually explained in terms of the standard alpha-omega mean field dynamo model where the local helicity generates a radial field component from an azimuthal field. The subsequent shearing of the radial field gives rise to exponentially growing dynamo modes. There are several problems with this model. The exponentiation time for the galactic dynamo is hard to c...
متن کاملDisk Tides and Accretion Runaway
It is suggested that tidal interaction of an accreting planetary embryo with the gaseous pre-planetary disk may provide a mechanism to breach the so-called runway limit during the formation of the giant planet cores. The disk tidal torque converts a would-be shepherding obj ect into a “predator”, which can continue to cannibalize the planet.esirnal disk. This is more likely to occur in the gian...
متن کاملpulsars torqued by accretion disk ?
The nature of AXPs/SGRs (anomalous X-ray pulsars/soft γ-ray repeaters) and high field radio pulsars is still unclear even in the magnetar and/or accretion models. The detection of radio emission from AXP XTE J1810−197 and the discovery of a debris disk around AXP 4U 0142+61 might shed light on the problem. We propose that AXPs/SGRs could be pulsars that have magnetic field B 10 13 G as normal p...
متن کاملMaxwell-chern-simons Electrodynamics on a Disk
The Maxwell-Chern-Simons (MCS) Lagrangian is the Maxwell Lagrangian augmented by the Chern-Simons (CS) term. In this paper, we study the MCS and Maxwell Lagrangians on a disk D. They are of interest for the quantum Hall effect, and also when the disk and its exterior are composed of different media. We show that quantization is not unique, but depends on a nonnegative parameter λ. 1/λ is the pe...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1985
ISSN: 0074-1809
DOI: 10.1017/s007418090007594x