Colgate, S. A., A phenomenological model of solar flares., ApJ, 221, 1068-1083 (1978) (ADS)
(click on the image for a larger version)
The celebrated Colgate "inductive flare" cartoon from 1978.
It is only a cartoon, of course, but the manner of opening the field lines
reminds one of Frances Tang's [1] "partial eruptions".
The Colgate paper first pointed out the likely foolishness of the
electron beam model "The so-called nonthermal X-rays... cannot be due to a
directed flux of electrons..." even with consideration of a
return current.
Colgate preferred to think of the hard X-rays as due to
a power-law distribution of emission measure in a thermal process
and daringly also suggested that the γ-rays come from runaway
protons as the current carriers.
The thermal/nonthermal dichotomy (for the electron distribution function)
persists as an important aspect of how we understand flare physics.
Compare this early cartoon with the more MHD-centric view of
Sturrock et al..
One can only admire this early epoch of solar-flare history, when really
interesting new ideas were forming.
Note that the Colgate and Sturrock cartoons both play fast and loose with the
current injection at the footpoints - how can the twist change rapidly,
if the massive interior of the Sun is dictating ∇ x B?
The celebrated Colgate "inductive flare" cartoon from 1978. It is only a cartoon, of course, but the manner of opening the field lines reminds one of Frances Tang's [1] "partial eruptions". The Colgate paper first pointed out the likely foolishness of the electron beam model "The so-called nonthermal X-rays... cannot be due to a directed flux of electrons..." even with consideration of a return current. Colgate preferred to think of the hard X-rays as due to a power-law distribution of emission measure in a thermal process and daringly also suggested that the γ-rays come from runaway protons as the current carriers. The thermal/nonthermal dichotomy (for the electron distribution function) persists as an important aspect of how we understand flare physics.
Compare this early cartoon with the more MHD-centric view of Sturrock et al.. One can only admire this early epoch of solar-flare history, when really interesting new ideas were forming. Note that the Colgate and Sturrock cartoons both play fast and loose with the current injection at the footpoints - how can the twist change rapidly, if the massive interior of the Sun is dictating ∇ x B?
[1] Frances Tang