X-ray of gamma-ray bursts observable by HEAO-B

On grounds of Mazetset al. (1980a) conclusion that all gamma-ray bursts recorded were emitted at the distance 1 kpc from the Sun it is shown that bursts from the Galaxy and from another galaxies may be observable byEinstein Observatory (HEAO-B). The HEAO-B observing programs are considered and the numbers of possibly recorded events are estimated. It is concluded that the important information about sources of gamma-bursts may be obtained in this way.     

S 10830 Trianguli – ein interessanter kataklymischer Veränderlicher

With the aid of silt spectrograms gained at the 6 meter telescope Selenchukskaja and at the 2 meter telescope Tautenburg a brightness outburst (the only one so far observed) could be followed up spectroscopically. The spectral behaviour resembles SS Cygni, but the presence of CIII and NIII emission is not typical of dwarf novae. Possibly the object is related to the anomalous recurrent nova WZ Sge. The definite determination of its belonging to a known subclass of cataclysmic variables will be possible only after obtainment of extensive photometric material.     

Periodic orbits around an oblate spheroid

The general properties of certain differential systems are used to prove the existence of periodic orbits for a particle around an oblate spheroid.In a fixed frame, there are periodic orbits only fori=0 andi near /2. Furthermore, the generating orbits are circles.In a rotating frame, there are three families of orbits: first a family of periodic orbits in the vicinity of the critical inclination; secondly a family of periodic orbits in the equatorial plane with 0<e<1; thirdly a family of periodic orbits for any value of the inclination ife=0.     

The spectrum of umbral oscillations of the Scheuer-Thomas sunspot model

Proper periods are calculated for oscillations of an isothermal gaseous layer with a homogeneous vertical magnetic field, limited by two rigid horizontal boundaries. The obtained results are in good agreement with the observed umbral oscillations in a sunspot.     

Evidence for a low-density inflationary universe?

The inflationary unvierse model predicts the density parameter ₀ to be 1.0 with the cosmological constant ₀ usually taken to be zero, whereas observational estimates give ₀0.2 and ₀10^-57 cm^–2. It was found, however, that the observed variation of angular diameter with redshift for extragalactic radio sources could be interpreted in terms of a low density universe with linear size evolution of the sources for either an inflationary model with 0 or an open model with =0.     

Effect of shocks on interstellar turbulence and cosmic-ray dynamics

A theoretical model for the interstellar turbulence is developed. In this model the fluctuation spectrum is formed due to reflection of shocks, produced by supernovae, on interstellar clouds. The spectra of turbulence and the diffusion coefficient of cosmic rays are derived. It is demonstrated that local enhancements of the ionization rate by cosmic rays accelerated by supernova shocks may be responsible for fast renewal of warm ionized envelopes around cores of standard ISM clouds.     

Observations of longperiod mass velocity oscillations in the Sun's chromosphere

Observations made by the differential method in the H line have revealed longperiod (on a timescale of 40 to 80 min) line-of-sight velocity oscillations which increase in amplitude with distance from the centre to the solar limb and, as we believe, give rise to prominence oscillations. As a test, we present some results of simultaneous observations at the photospheric level where such periods are absent.Oscillatory processes in the solar chromosphere have been studied by many authors. Previous efforts in this vein led to the detection of shortperiod oscillations in both the mass velocities and radiation intensity (Deubner, 1981). The oscillation periods obtained do not, normally, exceed 10–20 min (Dubov, 1978). More recently, Merkulenko and Mishina (1985), using filter observations in the H line, found intensity fluctuations with periods not exceeding 78 min. However, the observing technique they used does not exclude the possibility that those fluctuations were due to the influence of the Earth's atmosphere. It is also interesting to note that in spectra obtained by Merkulenko and Mishina (1985), the amplitude of the 3 min oscillations is anomalously small and the 5 min period is altogether absent, while the majority of other papers treating the brightness oscillations in the chromosphere, do not report such periods in the first place. So far, we are not aware of any other evidence concerning the longperiod velocity oscillations in the chromosphere on a timescale of 40–80 min.Longperiod oscillations in prominences (filaments) in the range from 40 to 80 min, as found by Bashkirtsev et al. (1983) and Bashkirtsev and Mashnich (1984, 1985), indicate that such oscillations can exist in both the chromosphere and the corona (Hollweg et al., 1982).In this note we report on experimental evidence for the existence of longperiod oscillations of mass velocity in the solar chromosphere.     

Accumulation and migration of the bodies from the zones of giant planets

Within the model of solid-body accumulation of planets (or their nuclei) the accumulation and migration of bodies from the feeding zones of the giant planets are investigated. The investigation is based on results of computer simulation of evolving disks which initially consisted of hundreds of particles moving about the Sun and coagulating under collisions. In some models the disks initially consisted of identical bodies. In other models they included also almost-formed planets. The computer simulation results as well as analytical investigations of the disk evolution depending on the number of particles in the disk allowed some estimates and conclusions on the accumulation process when the number of initial bodies was great (~ 10⁶–10¹²). In this paper the characteristics of an initial protoplanetary circumsolar cloud, the body migration in the forming solar system, the planet orbit evolution, the formation of the beyond-Neptune belt and asteroid belts between the giant planet orbits are considered. The results obtained confirm many analytical estimates earlier made by V. S. Safronov and his colleagues.     

Classification of lunar rocks and glasses by a new statistical technique

A new multivariate statistical technique have been developed for detection of populations groupings in data arrays. General characteristics of the method are described. Results obtained analyzing lunar rocks and glasses are discussed. Lunar rocks lie in a genetically related sequence: pyroxenitic mantle materials produce mare type basalts; anorthositic rocks are the most distant members of the differentiation; noritic, hi-Ti and high KREEP basalts materials appear to be intermediate products. Lunar glasses parallel the overall behaviour of rocks, with some peculiar local characteristics. Granitic materials are present only as glasses, suggesting an origin as residuals. Links between several identified classes are discussed in terms of the evolution of the lunar crust.     

Application of the Kalman filter to light curves of eclipsing binaries

Recently Kopal (1975a, b, c, d) initiated a new approach to the analysis of the light curves of eclipsing binary systems in which the solution is based on transforming the problem from the conventional time-domain into the frequency-domain. Irrespective of the type of eclipse, the present formulation of the frequency approach requires that a set of quantitiesA _2m, called moments, be determined from the observations.It is the purpose of the present paper to describe a data interpolation and smoothing technique based on a version of the Kalman filter to pre-process observations and to determine the quantitiesA _2m in an optimal sense.