Document 
A&A 482, 793-802 (2008)
DOI: 10.1051/0004-6361:20079043
Magnetohydrodynamic model of equatorial plasma torus in planetary nebulae
K. H. TsuiInstituto de Física - Universidade Federal Fluminense Campus da Praia Vermelha, Av. General Milton Tavares de Souza s/n Gragoatá, 24.210-346, Niterói, Rio de Janeiro, Brasil
e-mail: tsui@if.uff.br
(Received 9 November 2007 / Accepted 29 January 2008)
Abstract
Aims. Some basic structures in planetary nebulae are modeled as
self-organized magnetohydrodynamic (MHD) plasma configurations
with radial flow.
Methods. These configurations are described by time self-similar dynamics,
where space and time dependences of each physical variable
are in separable form. Axisymmetric toroidal MHD plasma configuration
is solved under the gravitational field of a central star of mass M.
Results. With an azimuthal magnetic field, this self-similar MHD model
provides an equatorial structure in the form of an axisymmetric
torus with nested and closed toroidal magnetic field lines.
In the absence of an azimuthal magnetic field, this formulation
models the basic features of bipolar planetary nebulae.
The evolution function, which accounts for the time evolution
of the system, has a bounded and an unbounded evolution track
governed respectively by a negative and positive energy density
constant H.
Key words: magnetohydrodynamics (MHD) -- methods: analytical -- stars: AGB and post-AGB -- ISM: planetary nebulae: general
© ESO 2008