Magnetohydrodynamic Model of Equatorial Plasma Torus in Planetary Nebulae

TL;DR

This paper presents a self-similar magnetohydrodynamic model for planetary nebulae, describing equatorial plasma tori and bipolar structures through axisymmetric configurations influenced by magnetic fields and gravitational forces.

Contribution

It introduces a novel self-similar MHD framework that models both equatorial tori and bipolar nebulae, incorporating magnetic fields and gravitational effects.

Findings

Models produce axisymmetric toroidal magnetic field lines.

Differentiates between bounded and unbounded evolution based on energy density.

Provides a unified MHD approach to planetary nebula structures.

Abstract

Some basic structures in planetary nebulae are modeled as self-organized magnetohydrodynamic (MHD) plasma configurations with radial flow. 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 $M$. 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 $H$.