*Astron. Astrophys. 326, 1277-1284*
**Available formats:** HTML |
PDF |
(gzipped) PostScript
## On collimation of the outflows in force-free magnetospheres
**I. Okamoto
**
Division of Theoretical Astrophysics,
National Astronomical Observatory,
Mitaka, Tokyo, 181 Japan
*Received 29 August 1996 / Accepted 9 June 1997*
**Abstract**
It is pointed out that ''an indeterminacy" claimed to exist in the *
pulsar equation* (Sulkanen & Lovelace 1990) or a ''free" function (Appl & Camenzind 1993a,b) can be uniquely related
to the stream function at the boundary of the force-free region to the load
region at infinity (Michel 1973b: Okamoto 1974). The form of is given
by from the plasma
conditions at infinity, where is the angular velocity of field lines.
This relation can be interpreted as indicating Ohm's law for the return current
from the equatorial region to the polar region on the 'sphere at infinity' with
finite resistivity Ohm, thereby ensuring the current
closure. The field structure tends to be asymptotically conical, toward
the 'sphere at infinity' and fields fill all the space there. It is argued that
force-free models for purely cylindrical jets cannot self-consistently conserve
electric current. The role of the plasma conditions in the black hole
equation is mentioned as well.
**Key words: **MHD - ISM: jets and outflows - galaxies: jets - Black hole
physics - pulsars: general
Send offprint requests to: I. Okamoto (okamoto@nao.ac.jp)
© European Southern Observatory (ESO) 1997
Online publication: October 1, 1997
Last change: April 8, 1998
helpdesk.link@springer.de |