On the role of energetic particles in solar flares

Abstract

The importance of energetic particles in the generation of solar flares and related phenomena has been underestimated if not completely neglected. A reexamination of their role in the light of recent observations carried out during the last solar maximum by a number of experiments on SMM and Hinotori satellites points out the continuous and violent evolution of the solar atmosphere. Most observed features can be better explained by the old idea that particles are trapped in magnetic loops above active regions where they are first heated and then accelerated by absorbing part of the wave energy flowing upwards continuously from the convection zone. Their catastrophic release into the chromosphere as a consequence of an instability in the region such as chromospheric heating or due to the emergence of new magnetic flux is considered as being the flare proper. Since the trapping of the particles involves the generation of resonant waves, a reassessment of the isotopic overabundance problem as well as a search for these waves in interplanetary space are proposed. Solar Physics 97 (1985) 131-144. 0038-0938/85.15. 9 1985 by D. Reidel Publishing Company

Solar Cosmic Rays

“…The instability of the magnetic trap may bring to the catastrophic release of particles into the chromosphere and the "ignition" of the flare proper. In contrast to the assumption of Elliot (1964) that the protons are acquiring the necessary energy slowly, during many hours or days, Perez-Enriquez (1985) showed that this process may take a few hours, and most observational features related to flares and particle acceleration are implicitly explained within such a new approach. The problem of this model is still, no doubt, that to this day no direct evidence exists for the presence of particles being accelerated in magnetic loops prior to the flare.…”

“…Therefore, it is important to consider in detail some of disputable aspects of the flare physics from the point of view of particle acceleration at the Sun. In this section we address one of them, namely, the possible role of non-thermal protons as a means of transporting energy in solar (stellar) atmosphere (see, e.g., Perez-Enriquez 1985;Simnett 1985Simnett , 1986Simnett , 1991Simnett , 1995.…”

“…As noted by Perez-Enriquez (1985), the importance of energetic particles in the generation of solar flares and related phenomena has been underestimated (if not completely neglected) up to the middle of 80s. He has proposed a solar flare model relying on the early hypothesis (Elliot 1964;Schatzman 1966, and others) about an active (if not decisive) role of energetic particles in solar flare generation.…”