Solar Energetic Particle Acceleration in Refracting Coronal Shock Waves
Vainio, Rami and Josef I. Khan, Solar Energetic Particle Acceleration in Refracting Coronal Shock Waves, ApJ, 600, 451-457 (2004) (ADS)
(click on the image for a larger version)
According to Uchida's suggestion of a fast-mode MHD blast wave in the
corona, as an explanation of type II bursts and
Moreton waves, there
should be a strong refractive effect on the wave propagation.
Specifically if the Alfvén speed increases into the corona, the skirt
of a global wave must tilt towards the chromosphere.
In this case, if the wave crosses open field lines, any particles it
accelerates may escape in the downstream direction, ie away from the
foreshock.
This seems like a fundamentally interesting new possibility.
Note that this cartoon centers the CME expansion within the streamer
(where else?) rather than off to one side as misleadingly sketched
in the Kahler-Ragot cartoon.
See also the recent Chrysaphi
cartoon.
According to Uchida's suggestion of a fast-mode MHD blast wave in the corona, as an explanation of type II bursts and Moreton waves, there should be a strong refractive effect on the wave propagation. Specifically if the Alfvén speed increases into the corona, the skirt of a global wave must tilt towards the chromosphere. In this case, if the wave crosses open field lines, any particles it accelerates may escape in the downstream direction, ie away from the foreshock. This seems like a fundamentally interesting new possibility. Note that this cartoon centers the CME expansion within the streamer (where else?) rather than off to one side as misleadingly sketched in the Kahler-Ragot cartoon. See also the recent Chrysaphi cartoon.