The appearance of isolated sunspot groups as well as clustering in large active regions depends upon a complex dynamo process. Evidence of this dynamo process may be deduced from three different outstanding studies. a) The emergence of new fluxes (spots or flares) is preceded by local cyclonic motions, observed at
the photospheric level. In regions of weak magnetic fields ; for example polarity inversion lines, gaps between magnetic "hills" or borders of the facula. This velocity structure is a response with a short scale in time and space to local subphotospheric perturbation and thus creates currents and new magnetic flux. b) Magnetic tracers such as long lived H filaments and sunspots, show that the regions of emergence of new flux (family of sunspot groups, eruptive sites or parasitic polaritics) are related to the existence of limited areas rotating rigidly. These "pivot points" which do not follow dlffcrential rotation, could be anchored more deeply than the active centers themselves. c) A large scale circulation, tied to the global rotation, reflects the motions of the underlying
fluid (frozen field). Recent results show the existence of azimuthal rolls which transport upward the deep magnetic field. They move slowly toward the poles, and they appear to govern the cyclicity
and to modulate the observed solar rotation. These observational results need to be considered to understand the production and the development of active regions.
Measurements of the proper niotlons of young blpolar sunspot groups show that these groups rotate faster than the surroundlng photosphere. The results of the tlme series analysis carrled out on the Irradiance records of the SMM/ACRIM radiometer and on the projected areas of the young, active sunspot groups showed a period near U days In 1980, the year of the solar maximum. The main period in the projected areas of the old sunspot groups was 28 days, which corresponded to the mean photospherlc rotatlon. The faster proper motlon of the young sunspot groups as well as the 24 days periodicity of the young active spot areas might indicate that the young sunspots are connected to the deeper regione of the Sun which rotate faster than the photosphere. Thus, the sunspot groups in the early stage of their life would be an indlcator of rotation of the deeper layers of the Sun.
In an extended region of recurrent groups of sunspots the relationships of spots and Hα flare occurrences were analysed on the basis of observations obtained in spring 1978. Principally new spot emergences and the relative motion of spots of opposite
magnetic polarities, belonging to unrelated bipolar spot pairs have been studied in a large activity complex lasting for several rotations. Further observational evidences were found that rapid motion of sunspots is essential to eruption of flares.
(In all speed data given the component of the differential rotation is eliminated.)
The resuits of the Hard X-Ray Imaging Spectrometer on the Solar Maximum Mission are reviewed. Particular emphasis ís given to those results which address phenomena which cannot easily be studied by the other instruments. Among the important discoveries are the following: it has been established that during the onset of the impulsive phase the hard X-rays are emitted from the footpoints of the flare loop, cospatial with the Hα kernels; very large, coronal loops, often containing plasma with temperatures up to 10^K,
are probably quasi-permanent features of the solar atmosphere; there are often soft X-ray precursors from points separated by ^ 10^ km which signal the onset of coronal mass ejections; following the onset of the impulsive phase hot plasma is observed to rise into the corona, sometimes inhibiting further energy input to the chromosphere; surges and prominences may be emitting weakly in soft X-rays during certain phases of their evolution; rapidly-varying
(^ 10‘s) soft X-ray spikes are occasionally seen, with unpredictable corresponding hard X-rays; and there has been a tentative identification of photospheric albedo, backscattered from the hard X-ray emitting plasma as it rises into the low corona.
Long-lived solar filaments published in Meudon catalogues for the time interval 1931-1987 are studied using a proper statistical method. Some results concerning the time distribution of the filament activity, filaments lifetime, cyclic behaviour and North/South asymmetry are obtained.
In quiescent prominences of a different brightness the full intensity ratios of He to H are varied in the different parts of the features. In the outside, more thin, parts of bright prominences or in the faint prominences a helium emission is stronger than hydrogen one. With a brightness increase the full intensity ratio of He to H is decreased. A modern interpretation of this ratio behaviour is connected with a fine filamentary structure of quiescent prominences. In this paper we consider a model filamentary feaaure, with different values fo structure coefficients, which consists of He and H atoms in excited and ionized states. We solve the non-LTE problem for the main transitions, coupled with the statistical equilibrium equations for a set of physical parameters typical for a quiescent prominence. As the result we compute He(3888) to Hα ratios and compare them with observations. We find this ratio to be sensitive to structural parameters, as some other ones.
Preliminary results of a search for the variation of the solar granulation properties with the heliographic laitude are presented. Within errors, no changes are found in the power spectra and sizes between N-S and E-W scans.