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We tackle the 2D models of Kuperus-Raadu and Kippenhahn-Schluter, extended by Malherbes and Priest, via the geometric methods of the theory of dynamical systems. We treat the models as phase portraits, and discuss them from the standpoint of mathematics only, without regard to physical significance. Some phase portraits are very intricated and we raise questions about them. We also suggest possible phase portraits. This paper tries to draw attention to new tools, used in celestial mechanics, as useful for the solar physics too and for a suitable interdisciplinary cooperation. [ABSTRACT FROM AUTHOR]

The heating of solar atmosphere from chromosphere to corona is one of the key fundamental and yet unresolved questions of modern space and plasma physics. In spite of the multi-fold efforts spanning over half a century including the many superb technological advances and theoretical developments (both analytical and computational) the unveiling of the subtle of coronal heating still remains an exciting job for the 21st century! In the present paper I review the various popular heating mechanisms put forward in the existing extensive literature. The heating processes are, somewhat arbitrarily, classified as hydrodynamic (HD), magnetohydrodynamic (MHD) or kinetic based on the model medium. These mechanisms are further divided based on the time scales of the ultimate dissipation involved (i.e. AC and DC heating, turbulent heating). In particular, attention is paid to discuss shock dissipation, Landau damping, mode coupling, resonant absorption, phase mixing, and, reconnection. Finally, I briefly review the various observational consequences of the many proposed heating mechanisms and confront them with high-resolution ground-based and satellite data currently available. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Hard X-ray emission during solar flares indicates usually presence of two or more sources, interpreted as regions of precipitation of non-thermal electrons propagating along the legs of the flaring magnetic loops. These sources often show asymmetry in hard X-ray fluxes. The brighter source is usually located in a weaker photospheric magnetic field region. For a simple interpretation a weaker convergence of magnetic field lines in a loop’s leg with a weaker magnetic field allows more electrons to reach the chromosphere. Another possibility is that the source of the energy release is located closer to one end of the loop. In this case this footpoint can be brighter in hard X-ray independently on the strength of the underlying magnetic field. In this paper we present example of a flare in which possible electron acceleration site is located asymmetrically, near one of the footpoint at the place where two magnetic loops interact. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]