Starting from flare models of Karličky (Solar Phys. 130, 1990, 347), we present the timedependent numerical simulations of hydrogen plasma excitation and ionization on subsecond time scales. These scales are consistent with the spiky behaviour of the kinetic temperature produced by non-thermal electron beam pulses of very short duration. Self-consistent numerical solution of
time-dependent, NLTE problem for a three-level plus continuum hydrogen atom allows us to predict theoretically the behaviour of
the Hα line intensity variations on subsecond time intervals. We present the Hα temporal profiles, evaluated at the line center and in the wing, which can be qualitatively compared with some recent flare observations obtained with very high (0.1 sec) temporal resolution. and Full version of this contribution was published in Solar Phys. 135 (1991), 65.
Two interacting active regions of different ages have been studied over two days using white light and Hα observations as well as magnetograma. Different series of homologous flares and the formation of a filament in tbe region were analysed and an interpretation of these events is proposed.
Hα filtergrams and GOES X-ray observations of four homologous flares of May 28, 1980 are analysed. The Hα data gave us information about the spatial structure of the flares. The X-ray data were used to determine the temperature of flare plasma and to investigate its time variations. We have found that the duration of the high plasma:temperature are approximalely equal for all the four analysed flares. The Hα-structure of these flares was complicated
nevertheless we have found only slight changes of the structure from flare to flare. These resulls suggest that a common reviving source of the energy release is responsible for all the four homologous flares. The individual flares are due to successive revivals of the energy source. The conditions of the energy flow along the magnetic field lines emerging from the energy source
determine which parts of the chromosphere are seen in the
Hα emission.
The 'Debrecen Photoheliographlc Results’ beginnlng with the year 1977 gives various kinds of posltion and area data of sunspots dally for a single moment, includlng all spot groups vlsible at least
on two days.In addition, thls catalogue also indicates tlie magnetlc spot polarities and for each sunspot, wherever reasonable, a special number as a mark of Identification. By these means special features of the spot activity of 1977 have been studied. So, diverse spot distributions and the principal spot motions within the groups, as well as the local solar rotatlon in several regions of spot groups by means of tracers of spot positions have been determlned. The most important characteristlcs found are presented.
Earlier results concerning sympathetic flares and time-correlated rádio bursts are compared with the history and dynamics of development of the magnetic situation in active regions with related flaring. An attempt to present observational evidence of the existence of sympathetic flares is made. We are trying to demonstrate that active regions producing such flares are physically related through common dynamical elements whose magnetic fields display parallel evolution.
The dynamical evolution of short-period comets, and in particular of those belonging to the so-called Jupiter family, is reviewed. Encounters with Jupiter play a dominant role in determining the
dynamical fate of these objects, although, in some peculiar cases, also interactions with other planets may be important. Frequent although temporary librations around resonances with Jupiter are displayed by more than one third of short-period comets. Integrations of motion of observed comets, over a time span comparable with their lifetime as active objects, are compared with previous numerical investigations, to get insight into the non observed phases of the dynamical evolution of these objects.
We investigated the structure of magnetic field and vertical electric currents in two active regions. Electric currents were calculated from the observations of transverse magnetic field. There exist two systems of vertical electric currents in an active region; a system of local currents and global one. The globál current is about 2.10^^ A. In the leading part of the active region it is directed upward, and in the tail - downward and is plausibly determined by the global rotation of plasma. The flare activity is dosely connected with the value and direction of both local and globál currents: the flares tend to appear in places with upward currents. The sensitivity of Hα„ emission to the sign of current implies that the charged particles accelerated in the upper parts of magnetic loops are responsible for these formations.