Linear polarization of precataclysmic variables

The optical linear polarization of three precataclysmic variables was measured in B and R. A noticeable polarization was detected only in BD +50°2869. In the other two cases, the polarization is probably interstellar in origin.     

Primeval turbulence from matter-antimatter annihilation

In a previous work by two of us, the main difficulties of the theory of galaxy formation from universal primordial cosmic turbulence were focussed; it was mainly found that the decay of the turbulence was so strong during the plasma era that turbulence should have been almost completely washed out before recombination, unless, and only for low-density universes, unlikely large turbulent velocities were postulated at the largest scale of the turbulence at the end of the radiation era. It was suggested that a possibility to turn around such a difficulty should consist in finding en adequate physical energy source feeding the turbulence during at least the whole plasma phase. The present work is intended to test whether matter-antimatter annihilation theory at the origin of the universe, as it is developed by Omnès and his collaborators, may be considered to yield the required energy source of the turbulence. To this aim, the main results of the work of Stecker and Puget concerning the behaviour of the most important quantities of the matter- antimatter annihilation theory are used, in order to describe the properties of the energy source for the turbulence down to recombination time, and extended to take a somewhat more detailed account of theirz and mean matter density dependences. The energy feeding source thus obtained is then introduced into the general framework of the galaxy formation theory from cosmic turbulence taking account of energy dissipation as developed in our previous works. The results obtained concerning the comparison of the main parameters of galaxies derived from the theory with the experimental data are much more satisfactory than in the previous approach, and show that, inside the errors of the present day values, sufficiently good fits are possible in a range of mean universe densities between 0.4 to 1 times the critical density.     

Unit cell parameters,compositions and 2V measurements of selected lunar plagioclases

Unit cell parameters of 12 selected lunar plagioclase specimens have been obtained using least-squares refinement of X-ray powder diffraction data. Compositions of splits of 11 of these plagioclase specimens were determined using the electron microprobe. Optical axial angles were measured on analyzed spots for nine of the probed specimens. Analyses cluster about An 96.5 ± 1.0 and unit cell parameters and 2V _x fit the values for this composition obtained in other studies.     

Microcrater populations on Apollo 17 rocks

Approximately 6000 microcrates were investigated using binocular microscope techniques on Apollo 17 rocks 70215, 72215, 72235, 72395, 72435, 73216, 73218, 73275, 74275, 76135, 76136 and 79155. The crater populations observed have identical characteristics to those obtained from previous missions.Special emphasis was placed on assessing the influence of target properties on the observable crater populations. Although these properties cannot be quantitatively evaluated at present, the empirical results indicate that crater populations on glass, breccia, and crystalline rock surfaces may differ fundamentally. As a consequence, lunar surface exposure ages of individual rocks based on micrometeoroid craters may be subject to criticism.     

On the cause of northward magnetic field along the negative X axis during magnetospheric substorms

The magnetic fields produced by a three-dimensional current system, consisting of a flow into the morning part of the auroral oval along tail-like field lines, along the auroral oval and out from the evening part of the oval along tail-like field lines, are computed. It is demonstrated that the major parts of the well-known ‘positive bay’ in low latitudes on the Earth's surface, the positive H variation at the synchronous distance and the positive B_s variation along the magnetotail during magnetospheric substorms can be caused by the proposed current system.     

A synoptic investigation of particle precipitation dynamics for 60 substorms in IQSY (1964–1965) and IASY (1969)

Sixty auroral absorption substorms (30 in IQSY and 30 in IASY) have been analysed on the basis of riometer-recordings taken at some 40 stations distributed over auroral, subauroral and polar cap latitudes. Synoptic maps showing isoabsorption curves have been produced every 15 min (sometimes every 5 min) of the 60 substorms; 705 maps altogether.Some of the results of the analysis are as follows.Initiation of a substorm most frequently occurs near midnight but may occur anywhere between early evening and late morning. The time of onset becomes earlier and the latitude of onset moves equatorward as the level of magnetic activity increases.The longitude expansion velocities are contained in the range 0.7–7 km/sec except for a few extreme values which exceed 20 km/sec.The auroral absorption eastward expansion velocity is smaller than the corresponding velocity of the boundary of the region of activation of the visual aurora after break up by a factor $\text{14}\text{?12}$.The expansion velocity corresponds, in general, to drift velocities of electrons of energies in the range 50–300 keV but, for the extreme speeds, electron energies around 1 MeV are needed.Expansion of the absorption in the westward direction was seen in about half of the substorms studied. In about half of these, expansion along the auroral oval could be indentified, but in almost all of these cases some expansion in the auroral zone latitudes was also seen. In about an equal number of events, expansion was confined primarily to the auroral zone.The velocity of the westward expansion was about 1 km/sec along the auroral oval (i.e. approximately equal with the speed of the westward travelling surge) but about 2 km/sec along the auroral zone.The meridional expansion velocities found agree well with those measured for visual aurora (? 1 km/sec).The variability of the behaviour of different substorms is very large. To illuminate this the following may be mentioned, in addition to what has been stated above about the statistics.Although the absorption maximum practically always moves eastward from the initiation region, exceptions have been seen in which the maximum started moving west and in a later phase went eastward.Sometimes the absorption maximum stays in the injection area or very close to it, although in most cases it moves eastward into the dayside. In extreme eases it has been found to move more than 270° in the eastward direction.There are auroral absorption substorms in which injection seems to take place in more than one area simultaneously.The observations cannot all be understood in terms of gradient and curvature drift of electrons from a small area of injection only. A broad intrusion of hot plasma from the tail into the inner magnetosphere seems to be needed.No strong dependence of particle precipitation on the illumination of the upper ionosphere by sunlight was seen. The results do, therefore, not support the hypothesis of Brice and Lucas (1971) that cold plasma density increases, originating in the ionosphere, significantly increase the precipitation rate of energetic trapped particles.     

Interferometric measurements of the λ 7319 Å doublet emissions of OII

Fabry-Perot interferometer observations of the OII 7319 Å line made from College, Alaska are presented. Significant Doppler shifts corresponding to the ion drift motion, caused by the convection electric fields, were observed under special conditions, but no steady observations were possible due to the sporadic nature of this emission. Very preliminary results of the observed doublet separation (≈0.836 Å) are also presented.     

Fluctuations of electron precipitation to the dayside auroral zone modulated by compression and expansion of the magnetosphere

Concurrent variations of CNA fluctuations and geomagnetic fluctuations are classified into Type 1 (substorm-type), Type 2 (Pc5-type), and Type 3 which is the object of the present study. Type 3 apparently has peculiar characteristics in that CNA fluctuations at a certain auroral-zone station show a pronounced positive correlation with magnetic fluctuations at distant low-latitude stations. The magnetic fluctuations of this type are identified to generalized Si which tends to take place much more frequently than the so-called Si. The CNA fluctuations of this type are found to take place on the dayside auroral zone only when preceded by a magnetic substorm on the night side. Considering the change of the growth rate of electron cyclotron instability and enhancement of pitch angle diffusion due to the change of magnetic field intensity, the following model is proposed to explain the occurrence mechanism of Type 3 concurrent variations. The CNA fluctuations take place only when two conditions are satisfied; generation of the accelerated electrons in association with substorm onset and modulation of the precipitation of the electrons by compression and expansion of the magnetosphere, in other words, by generalized Si.     

Radiating spherical collapse with shear and heat flow

We consider a spherical body consisting of a fluid with heat flow which radiates in its exterior a null fluid described by the outgoing Vaidya's metric, we prove that this solution matched with the outgoing Vaidya's metric represents a physically reasonable collapsing model. Our model has the remarkable property: it is shear-free and the motion of the fluid is geodesic.CNPq-allowance.