On Some Characteristic Features of Type IV Bursts. Part Ill
Abstract
On the 14th September 1966 a radio solar event was observed by Boischot and Clavelier on the west limb of the Sun. It was a moving type W burst, which emitted synchrotron radiation and maintained a constant source size; it appeared in the corona at a height of 1 Re above the photosphere, and moved with a constant speed of 530 km/s up to 1.7 Re where it spread and disappeared. With the values of the electron density, temperature and magnetic field generally used in the corona, we find that the source appears and disappears for critical values of the Mach number corresponding to the values for collisionless shock waves given by the theory of Sagdeev and Galeev. The observations of such an event seem to prove that electrons can be accelerated in the shock wave high in the corona: using theoretical works by Kadomtsev and by Tsytovich we show that a statistical acceleration is possible if we suppose that a stationary energy spectrum of turbulent ion acoustic waves, isotropic in wave vector space, is excited in the shock front.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 March 1969
 Bibcode:
 1969A&A.....1..325L