Welsch, Brian T., Flux Accretion and Coronal Mass Ejection Dynamics, Sol. Phys., 293, 113 (2018) (ADS)
(click on the image for a larger version)
A painstakingly clear mapping of the connectivity involved in an
erupting bipolar structure, clearly identifying its 3D properties
in a series of projections onto 2D.
This captures the essence of the
Hirayama cartoon
without diversionary gestures towards filaments, the chromosphere, etc.,
with a pre-existing sheared (finite guide field) state.
The cartoon shows top views (top row) and end-on views (ie, along the
magnetic inversion line, dashed in black) in the bottom row.
The heavy blue line is the sheared flux tube that erupts, and in the three
time steps (left to right) it reconnects through the magenta field
line (shown as solid before and dashed after reconnection, lower
middle), and then as a four-footpoint pair of field lines in the
final panel.
This could be described felicitously as magentic reconnection, and
the cartoon makes the important point that this requirement
of four participating footpoints actually does represent a factor
of two in the reconnection flux, a point
often omitted from discussions
of this topic.
A painstakingly clear mapping of the connectivity involved in an erupting bipolar structure, clearly identifying its 3D properties in a series of projections onto 2D. This captures the essence of the Hirayama cartoon without diversionary gestures towards filaments, the chromosphere, etc., with a pre-existing sheared (finite guide field) state.
The cartoon shows top views (top row) and end-on views (ie, along the magnetic inversion line, dashed in black) in the bottom row. The heavy blue line is the sheared flux tube that erupts, and in the three time steps (left to right) it reconnects through the magenta field line (shown as solid before and dashed after reconnection, lower middle), and then as a four-footpoint pair of field lines in the final panel. This could be described felicitously as magentic reconnection, and the cartoon makes the important point that this requirement of four participating footpoints actually does represent a factor of two in the reconnection flux, a point often omitted from discussions of this topic.