The simulations present a first cut as understanding how a
disk interacts with a magnetosphere. Three movies are presented
from a fiducial simulation of a 3keV accretion disk interacting
with the magnetic field of a 1.4 solar mass neutron star. The
star initially has a dipolar magnetic field. The first movie
shows the log of the density. The second movie shows the
evolution of the flow velocity vectors with a color overlay
showing the magnitude of the velocity. The third movie shows the evolution
of the magnetic field, where, as before, the vectors show the
direction of the magnetic field and the color shows the strength of
the field. The movies show the r-theta half-plane (0 < theta < pi/2).
Alfven wave interaction between the disk and the halo sets off
an initial transient. After that, the disk settles into a pattern
of accretion. We see that the flow develops initially pinches the
field, making it possible for a certain fraction of the disk's
matter to be ejected magnetocentrifugally. The rest of the
matter threads the magnetic field and sets up motions that begin
to fill the magnetosphere. Notice that the accretion on to the
polecap is not steady state, but rather strongly episodic.
This clearly shows that a one-zone model of this scenario would
eventually prove inadequate and the only way to do this problem
is to make a self-consistent integration of the dynamical
code with the nuclear reaction network codes, a JINA goal which
we are pursuing.