Syrovatskii, S. I., Pinch sheets and reconnection in astrophysics, ARA&A, 19, 163-229 (1981) (ADS)
(click on the image for a larger version)
Syrovatskii was one of the great pioneers of electrodynamic theories of
astrophysical processes, and this cartoon illustrates the
separator/separatrix domain structure of the coronal magnetic field
as introduced by Giovanelli.
Here the dashed line is the singular separator line in a "quadrupolar"
configuration, the locus of a current that links two regions in
the photosphere.
It is odd, but these ancient ideas are now central again in MHD theories
of solar flares; the 2D paradigm that is the basis of so many of the
cartoons in this Archive is no longer as actively pursued, and one
can hear the occasional pundit acknowledge that 3D is "entirely
different" from 2D, never mind their earlier exclamations about success
in the 2D modeling!
The Archivist would question the singularity of the separator current.
Surely it arises in the photosphere and closes there, manifested
in the solar interior as ∇ x B.
But why should that be localized so sharply, and why should the two
ends of the separator have the exact match required by charge neutrality
in the steady state?
This sketch appeared in Syrovatskii's
Annual Reviews article [1] of 1980;
it was completed posthumously by his colleagues.
Syrovatskii was one of the great pioneers of electrodynamic theories of astrophysical processes, and this cartoon illustrates the separator/separatrix domain structure of the coronal magnetic field as introduced by Giovanelli. Here the dashed line is the singular separator line in a "quadrupolar" configuration, the locus of a current that links two regions in the photosphere. It is odd, but these ancient ideas are now central again in MHD theories of solar flares; the 2D paradigm that is the basis of so many of the cartoons in this Archive is no longer as actively pursued, and one can hear the occasional pundit acknowledge that 3D is "entirely different" from 2D, never mind their earlier exclamations about success in the 2D modeling!
The Archivist would question the singularity of the separator current. Surely it arises in the photosphere and closes there, manifested in the solar interior as ∇ x B. But why should that be localized so sharply, and why should the two ends of the separator have the exact match required by charge neutrality in the steady state?
This sketch appeared in Syrovatskii's Annual Reviews article [1] of 1980; it was completed posthumously by his colleagues.
[1] Syrovatskii 1980