Gold, T. and F. Hoyle, On the origin of solar flares, MNRAS, 120, 89 (1960) (ADS)
(click on the image for a larger version)
The original reference about the interaction of two current-carrying
loops in the solar chromosphere.
This paper still reads quite well,
after sixty years, since it considers the hard problems of stability
and energetics from first principles.
It was a bit of a shock for the Archivist to
re-read it and find that they were explaining chromospheric flares,
which allowed them to get away with non-force-free conditions at
the boundaries of their famous twisted loops.
It might seem somewhat
off the point, since we now more or less believe that the real
action takes place in the low-beta corona, where the coronal field
is all-pervasive and does not admit flux ropes with external
boundaries as Gold and Hoyle propose (see the
Georgoulis cartoon describing
non-neutralized currents).
On the other hand, we often
really do see the most powerful energy releases in very compact
structures, so maybe the non-force-free domain does play a role.
Note that this concept of "loop-loop interactions" subsequently generated
a lot of literature, but perhaps not so relevant - if the active-region
corona really has low plasma beta, then any flux surface containing higher
gas pressure should actually be an anti-loop (a shallow magnetic
tunnel, rather than a loop of more intense field.
Finally, does co-helicity or counter-helicity favor interaction?
In any case, from the design point of view, this cartoon is brilliant and
still often shown.
Does co-helicity or counter-helicity favor interaction?
The original reference about the interaction of two current-carrying loops in the solar chromosphere. This paper still reads quite well, after sixty years, since it considers the hard problems of stability and energetics from first principles. It was a bit of a shock for the Archivist to re-read it and find that they were explaining chromospheric flares, which allowed them to get away with non-force-free conditions at the boundaries of their famous twisted loops. It might seem somewhat off the point, since we now more or less believe that the real action takes place in the low-beta corona, where the coronal field is all-pervasive and does not admit flux ropes with external boundaries as Gold and Hoyle propose (see the Georgoulis cartoon describing non-neutralized currents). On the other hand, we often really do see the most powerful energy releases in very compact structures, so maybe the non-force-free domain does play a role.
Note that this concept of "loop-loop interactions" subsequently generated a lot of literature, but perhaps not so relevant - if the active-region corona really has low plasma beta, then any flux surface containing higher gas pressure should actually be an anti-loop (a shallow magnetic tunnel, rather than a loop of more intense field. Finally, does co-helicity or counter-helicity favor interaction?
In any case, from the design point of view, this cartoon is brilliant and still often shown. Does co-helicity or counter-helicity favor interaction?