Die angeführten Tafeln sollen mittels des siderischen Jahres den Übergang verschiedener Epochen für das Jahr 1950,0 und umgekehrt erleichtern. Sie sind vor allem für die Falldaten-Vergleichung der Meteorströme bestimmt. Die Epochen der maximalen Tätigkeit der Hauptströme für 1950,0 enthält die Tafel II. and Na straně 13 jsou uvedena shrnutí (Zusammenfassung) k oběma článkům čísla v němčině
The model has 4 components: the extragalactic background, the radiation from the galactic disc and 2 components related to a spur. It fits observations while the hypothetical radio halo does not.
The dust production rates of all the known periodic comets, calibrated by the measurements from the 1986 apparition of comet Halley, are ušed to compute their dust input into the region inside the earth orbit, and the resulting dust fluxes at R = 1 AU. The spatial distribution of tho fresh ejecta and the teraporal variations of their accumulation are reconstructed. Tho visible release of dust is evidently insufficient to maintain the zodiacal cloud in equilibrium.
It is suggested that the progressive decay of the dark matter, including extinct cometary nuclei, their fragments, and products of asteroidal collisions, represents the dominant source of
replenishmont of the interplanetary dust complex.
Most of the work on exact models representing gravitational waves in general relativity has been concerned with spacetimes which are,at least in some directions, asymptotically flat. Here we treat gravitational waves in one of the simplest but everywhere curved cosmological model. We give the physical interpretation of exact "type - N solutions" of Einstein´s equations with cosmological constant presented recently by García Días and Plebanski. We show that some of these solutions may be interpreted as gravitational waves propagating in the de Sitter universe. (According to present consensus, this unvierse represents the inflationary stage of our Universe.) The analysis also reveals that tha solutions can serve as the illustration of the cosmological no-hair theorem: they approach the de Sitter space-time asymptotically in time.
We present preliminary results from a spectroscopic survey for absorption line profile variations among the O stars. Our data consist of more than 1000 high quality spectra of 46 bright O stars which were obtained with sufficient time resolution to sample variations with timescales of hours to days. Most spectral types and luminosity classes are represented. We find that about 31% of these stars exhibit photospheric variability which probably arises from organized velocity fields. The remaining stars are either constant (31% of the sample) or possess variability associated with their winds (43% of the sample, including 2 of the photospheric variables). We present examples illustrating each of these classes of behaviour, and discuss preliminary implications and future
directions of this work.
The complex space experiment Phobos will consist of two space probes carrying more than twenty experiments each. The primary purpose of the mission, launched in June 198B, is the exploration of the Mars satellite Phobos and of the planet itself. Various methods are used, including landing on the satellite and activation of its surface minerals by laser beam. During orbiting around Mars, the atmosphere of the planet will be studied. The secondary purpose is to study solar activity during the flight from Earth to Mars, gathering informations on solar wind, interplanetary shock waves, and gamma bursts. Solar X-ray activity will be monitored and solar
corona observed in X-rays; stereoscopic studies of the Sun will be made. The coordinator of the experiment is the Space Research Institute of the Academy of Sciences of the USSR, the other participants are from Austria, Bulgaria, Czechoslovakia, Finland, France, German Democratic Republic, German Federal Republic,
Hungary, Poland, Sweden, Switzerland and ESA.
The problem of interpretation of the so-called Central Void /CV/ in the Jagiellonian Field /JF/ is consldered. The galaxies in JF are inclined to group around CV into a pallium-like configuration. The popular suggestion that CV may reflects a really existlng and genuinely empty volume of the inter-multicluster space has been verified. So far any interstellar cloud was nover regarded as a possiblo explanation because of: 1. the cosecant-type laws descrlbing interstellar extlnctlon in the Milky Way, whlch made the galactlc extlnction at b=72” improbable, 2. the claims of the Zwicky´s School that JF was free of the extlnction, 3. the traditlonal view that multlclustering was not caused by absorptive dusty clouds, i.e. that the extended galaxy structures were not only apparent. The results of our work concem the conceptual foundatlons of the researoh programme oontained in early works of Splawa-Neyman /superclustors of galaxies called "clouds"/ and recent searches of Batuski and Burns on a poasible 300 Mpc filament of clusters of galaxies in Perseus-Pegasus. In the paper It ia proved that a local dusty cloud Is projected just onto the region of the Central Void.