Super-Fast Line-Profile Variability in the Spectra of OBA-Stars: B1-Star <Emphasis Type="Italic">ρ</Emphasis> Leo

This study continues our investigation of the super-fast variability of line profiles in the spectra of early-type stars. We have investigated the line-profile variability in spectra of OBA-stars with the SCORPIO multi-mode focal reducer mounted at the 6-m SAO RAS telescope. Regular short-period variations of the H and He lines in the spectra of the B1I star ρ Leo were detected with periods ranging from 2 to 90 minutes, as well as irregular line-profile variations on time intervals less than 1 minute. A possible origin of rapid spectral variations is discussed.     

Estimates of abundance of the short-baseline (1-3 meters) slopes for different Venusian terrains using terrestrial analogues

The interplanetary mission, Venera-D, which is currently being planned, includes a lander. For a successful landing, it is necessary to estimate the frequency distributions of slopes of the Venusian surface at baselines that are comparable with the horizontal dimensions of lander (1–3 m). The available data on the topographic variations on Venus preclude estimates of the frequency of the short-wavelength slopes. In our study, we applied high-resolution digital terrain models (DTM) for specific areas in Iceland to estimate the slopes on Venus. The Iceland DTMs have 0.5 m spatial and 0.1 m vertical resolution. From the set of these DTMs, we have selected those that morphologically resemble typical landscapes on Venus such as tessera, shield, regional, lobate, and smooth plains. The mode of the frequency distribution of slopes on the model tessera terrain is within a 30°–40° range and a fraction of the surface has slopes <7°, which is considered as the upper safety limit. This is the primary interest. The frequency distribution of slopes on the model tessera is not changed significantly as the baseline is changed from 1 m to 3 m. The terrestrial surfaces that model shield and regional plains on Venus have a prominent slope distribution mode between 8°–20° and the fraction of the surfaces with slopes <7° is less than 30% on both 1 m and 3 m baselines. A narrow, left-shifted histogram characterizes the model smooth plains surfaces. The fraction of surfaces with slopes <7° is about 65–75% for the shorter baseline (1 m). At the longer baseline, the fraction of the shallow-sloped surfaces is increased and fraction of the steep slopes is decreased significantly. The fraction of surfaces with slopes <7° for the 3-m baseline is about 75–88% for the terrains that model both lobate and smooth plains.     

Technologies of measurements of the sea level

We analyze the contemporary methods and means of measurements of the sea level and inland waters, describe a CTD-meter designed at the Marine Hydrophysical Institute of the Ukrainian National of Science for the determination of the sea level, formulate the requirements to the perfect meter of the water level, and demonstrate that an electronic sounding stick based on the distributed Walsh thermoprofilometers can play the role of a device of this kind.     

Radial velocity and magnetic field measurements of the a-type supergiant ν cep (HD 207260)

On the basis of 55 Zeeman spectrograms obtained at Tautenburg in the years 1975–1979 the effective magnetic fields and the radial velocities of the supergiant ν Cep (HD 207260) were determined. For the effective magnetic field a slow variation occurring on a time scale of years was found. The spectrograms taken at the first time show only moderate effective magnetic field strengths of a few hundred Gauß, but in the year 1978 values of +2000 Gauß were detected. The measured radial velocities show a longtime variability similar to that of the magnetic field as well as more rapid changes. A periodical variation of the radial velocity with a period of ∼ 39.9 days, perhaps produced by the rotation of the star, is indicated. The Balmer absorption lines H_β, H_β, and H_δ have different radial velocities refering to the presence of an expanding envelope. Moreover, there exist significant differences between the velocities of various elements respectively ions of 1–4 km/s.     

Regional variations in cleavage and fold development in North Wales

The arcuate pattern of the main Caledonian cleavage and associated fold axial plane traces in North Wales is due partly to NW-SE compression with tectonic transport to the southeast against the concealed crop of the Tan y grisiau Microgranite. Low-angle cleavage close to the microgranite is shown to be a local variant of the regional cleavage formed during the main deformation and not an earlier phase as previously supposed. Transcurrent movements along several major fault systems are also related to compression around the microgranite and the Harlech Dome block.