Synthetic spectra computed svith semiempirical and theoretical models of the flare atmosphere are discussed. Stark profile of the Dahner lines ( n ≥ 6) and the Balmer continuum have been computed according to Donati-Falchi et al., (1985). A semiempirical model in between the F2 and F3 models proposed by Avrett et al., (1986) might represent a good approximation of the atmosphere of a flare during the impusive phase. Among the theoretical models proposed by Ricchiazzi (1982), the model, indicated as 1073, with very high coronal pressure (Po = 1000 dyne cm–2) probably represents the best approximation of the emission observed during the impulsive phase of a chromospheric flare. Continuum and Balmer lines ought to be measured and interpreted on the same time for a self-consistent diagnostic of the chromospheric modification.

Periodic Doppler motions inside small fluxtubes are determined from the zero-crossing point of the circular Zeeman polarization profile (Stokes-V=0). The gas fully participates on the known solar 5min oscillations without affecting amplitude or frequency. Averaging the oscillations, the gas is at rest in an absolute solar scale. Discrepancies with formerly observed redshifts are explained by the systematic westward displacement of the magnetic structure relative to the Ca+K bright point used for guiding.

We discuss an ordinary differential equation which describes how the pressure in a coronal loop may evolve in time under the influence of a uniform, but time varying heating rate.

It has been proposed that non-thermal ions dominate the energy transfer at the onset of solar flares. Here we examine this hypothesis in the context of flares on dMe stars. If the magnetic field in the stellar corona is significantly larger than that in the solar corona, and if strong fields in the photosphere, analagous to active regions, are absent, then a self-consistent explanation of stellar flares may be formulated.

The formation of the Lyman and Balmer lines of Hydrogen at densities typical in dMe stars is shown to be very dependent on the atomic model used viz. the number of levels and line transitions. The effect of increasing the number of levels and line transitions on the line fluxes and ionization fraction is also discussed.

I give here a short review of some of the main problems of the magnetic theories for the flare origin. I point out that the magnetic theories are unable to solve the problems of the energetics, height and compactness of the acceleration region, compresslve inflows, magnetic field structures, particle numbers, preflare upflows and the global cause of the flare origin. Then I outline the convective flare theory which have proposals for the solutions of these problems. I show here what is the role of the magnetic field at flare origins in the frame of the convective flare theory. The convective flare theory gives a deeper level understanding than the magnetic theories and therefore it also can supply us with the derivation of some input parameters and assumptions used for the magnetic theories and so it offers a wider perspective to understand the physics of the explosive astrophysical processes.

We have computed kineamtic dynamo models for the Sun making realistic assumptions about the different induction effects. Recent results of helioseismology are used to infer the differential rotation. By changing the value of the angular velocity at the bottom of the convection zone in the models we find more or less agreement with the observations.