[en] Daily scanning of the solar corona in the years 1968 to 1980 showed that in some heliographic latitudes plasma flowed faster while in some others it flowed more slowly, this by roughly +-3 m/s. The development of these currents seems to be clearly associated with solar activity. Fast currents appear in the poles at the minimum of solar activity and gradually descend to the equator. After about 11 years they reach the upper limit of the band where sunspots may occur (+-35deg) and after another 11 year period they pass through the band only to join together at the equator and disappear. The discovery of currents on the solar surface seems to represent a long time expected and sought connect.ing link between the internal Sun's structure and the solar activity cycles. (J.B.)

[en] The book is devoted to the life and work of Christian Doppler and particularly to his links to Prague and to the Slovak town of Banska Stiavnica. Many historical facts concerning Doppler's activities as well as the history of physics and astronomy are collected. Information is also presented about the Czech Technical University, the Society of Czechoslovak Mathematicians and Physicists, the Czechoslovak Astronomical Society, the Czechoslovak Spectroscopic Society and the Czechoslovak Society for the History of Science and Technology. The publication is amply supplemented with historical pictorial material (M.D.). 92 figs., 82 refs

[en] A review is given of the exponential decay law of excited nuclei and molecules, treated in terms of the concept of rapid intranuclear and intramolecular processes in which statistical redistributions and fluctuations of energy occur. Deviations from the exponential decay law that would indicate sequential quenching of the memory of unstable systems have not been so far observed. (author). 1 fig., 34 refs

No abstract available

[en] Absorption features of irradiated quartz and other silicates of tetrahedron structure are studied in this paper. The possibility that these materials can be one of the main contributors responsible for many of the observed features in the visible region at low temperatures is discussed. (Auth.)

[en] The correlation between the rapid rise of intrinsic polarization, increasing U-B and enhanced equivalent width of Balmer, H and K emission lines is interpreted as a consequence of the activation of colour centres in circumstellar silicate dust by X/UV photons from flares. The temperature dependence of bleaching is discussed and the number of centres producing polarization changes is estimated. (Auth.)

No abstract available

[en] Progress is reported in evaluating the mass spectra of cometary dust grains that have been obtained by impact mass analyzers flown onboard the Giotto and Vega spacecrafts. Statistical analysis of about 5000 spectra transmitted to the Earth in the more compressed modes 1 to 3 demonstrates that the mean elemental composition is similar to that of Cl carbonaceous chondrites with the exception of the light elements C, H, O, and N which approximate solar composition. The isotopic ratios do not differ from solar system values. Five classes of particles are suggested: 1) with dominant Mg-Si element group, 2) with dominant CHON abundances, 3) composites of classes 1 and 2, 4) grains rich in carbon, 5) grains rich in iron and sulphur. (author). 4 figs., 1 tab., 6 refs