An analytical MHD wind model with latitudinal dependences obtained using separation of the variables

¹ Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
² Departamento de Matemática Aplicada, Faculdade de Ciências, Universidade do Porto, Portugal
³ School of Mathematical and Computational Sciences, University of St. Andrews, St. Andrews KY16 9SS, Scotland, UK e-mail: eric@mcs.st-and.ac.uk
⁴ Department of Physics, University of Crete and FORTH, PO Box 2208, 71003 Heraklion, Crete, Greece e-mail: tsingan@physics.uoc.gr

Corresponding author: J. J. G. Lima, jlima@astro.up.pt

Received: 12 May 2000
Accepted: 28 February 2001

Abstract

A new class of analytical 2-D solutions of the full set of the steady magnetohydrodynamic (MHD) equations, describing an axisymmetric helicoidal magnetized outflow originating from a rotating central object, is presented. The solutions are systematically obtained via a nonlinear separation of the variables in the momentum equation. The analysis yields three parameters which measure the anisotropy in the latitudinal distribution of various flow quantities. Topologically, the wind speed is controlled by an X-type critical point that acts to filter out a single wind-type branch and the Alfvén singularity. The solutions can be regarded as an extension outside the equatorial plane of the Weber & Davis ([CITE]) model of magnetized winds but with a variable polytropic index.