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The offset of the center of mass of the moon from its center of figure together with moment of inertia differences are explainable by a lunar crust of randomly varying thickness. The necessity of postulating a method of preferential material transport into a particular lunar hemisphere to explain the lunar asymmetry is eliminated.
An earlier model of the Jovian magnetosphere is utilized in which the centrifugal stress of corotating plasma distends the outer magnetosphere and opens the tail field. Because of a longitudinal asymmetry in the ionospheric plasma source strength, caused principally by the nonaxisymmetric surface field, the closed-field region in the tail expands and contracts with the rotation period, resulting in a 10-hour modulation of the flux of energetic particles escaping from the magnetosphere into interplanetary space.
The effects of tilt and structural asymmetry on the vibration characteristics of partly liquid-filled thin-wall cylinders were experimentally studied. It was found that tilting the longitudinal axis of a partly filled axisymmetric cylinder from the vertical could markedly reduce its resonant frequencies and change significantly the shape of the circumferential modes. For the minimum frequency modes, vibratory motion occurred only on that side of the cylinder where the liquid was deepest. An empirical equation was derived that gives the equivalent liquid depth of an untilted cylinder having the same minimum resonant frequency as a tilted, partly filled cylinder. Circumferential mode shapes of an untilted asymmetric cylinder were similar to those of the tilted, partly filled axisymmetric cylinder. Vibratory motion in the minimum frequency modes occurred in most instances only on the side of minimum thickness. Correlation between test data and results from a reformulated NASTRAN hydroelastic analysis was excellent.
The structures of Earth, Mars, Venus, and the Moon are examined and compared. Global tectonic characteristics are presented for each. A comparison of the tectonics reveals the structural asymetry of these planets and the moon. Tectonic asymmetry information for the group is used to interpret certain aspects of the earth's geological past.
An investigation has been undertaken to determine whether ionizing radiation might engender racemization of optically active amino acids, along with their usual radiolysis. As prototypes, crystalline Dand L-leucine, as well as aqueous solutions of their sodium salts were exposed to the radiation from a 3000 Ci Co-60 gamma-ray source. Gamma-ray doses which caused about 68% radiolysis of solid leucine left a residue which was about 5% racemized, while racemization proved even greater at lower doses for the dissolved sodium salts. In aqueous solution both percent degradation and percent racemization of the sodium salts were proportional to gamma-ray dosage within the range employed (1,000,000-27,000,000 rads). Implications of these observations for the origin of molecular asymmetry by the beta-decay parity violation mechanism are discussed.
An explanation of the east-west asymmetries of Io's sodium clouds is suggested based upon the force experienced by sodium atoms as they resonantly scatter sunlight and upon the ability of this force to alter the cloud atom orbits, as determined by the gravitational fields of Io and Jupiter. Orbit calculations illustrating the time-dependent changes in the sodium atom trajectories produced by the solar radiation force as a function of Io's orbital location are presented in support of this explanation. This theory agrees with the idea that sodium atoms are emitted from the satellite nonisotropically and at a constant rate. These conclusions may be important in studying the global effects of active volcanoes and the intense satellite plasma torus discovered for Io from Voyager I spacecraft measurements.
A strong longitude variation in the midlatitude Lyman-alpha brightness of Jupiter has been discovered using data from the Voyager ultraviolet spectrometers. A minimum brightness of 14.4 kR was observed in the System III (1965) west longitude range 200-300 deg. The intensity rises to a broad peak of 19.6 kR near a longitude of 110 deg, a 36% increase over the minimum. This intensity 'bulge' was observed to rotate with the planet and appeared at the same longitude during both Voyager encounters, four months apart. This is a surprising discovery; no other planet studied to date has such a characteristic and the upper levels of the Jovian atmosphere were expected to be uniform in longitude. It is likely that a longitudinal asymmetry in charged particle precipitation leads to selective heating of the upper atmosphere and increased dissociation of H2, increasing the hydrogen column abundance. The resulting increase in resonant scattering could produce the observed intensity bulge.
Cosmic matter-antimatter asymmetry due to the gravitational interaction alone is discussed, considering the gravitational coupling of fermion matter related to the Yang-Mills (1954) gauge symmetry with the unique generalization of the four-dimensional Poincare group. Attention is given to the case of weak static fields which determines the space-time metric where only large source terms are retained. In addition, considering lowest-order Feynman diagrams, there are presented gravitational potential energies between fermions, between antifermions, and between a fermion and an antifermion. It is concluded that the gravitational force between matter is different from that between antimatter; implications from this concerning the evolution of the universe are discussed.
Evidence of three kinds indicates a lunar compositional asymmetry: mare basalts are much more abundant on the near side; the incompatible rich KREEP component is mainly observed in near-side soils; and materials on the far side are less dense than those of the near side, as indicated by the 2-km offset between the center of mass and center of figure. Recent models to explain the 2-km offset are based on near side-far side differences in the thickness of crustal units. The most widely discussed model calls for a thickness of anorthosite of about 24 km greater on the far side than on the near side, but no satisfactory method of generating such a large difference has been proposed. It is suggested that much of the offset reflects longitudinal differences in mantle composition, primarily resulting from earlier (or more rapid) crystallization of the magma ocean on what is not the far-side hemisphere. As a result, the far-side mantle would be more magnesian and thus less dense than the near-side mantle.
Voyager 1 images of Titan, when normalized to remove limb darkening, reveal an axially symmetric brightness pattern with significant north-south asymmetry. This interhemispheric contrast seems to be a response to seasonal solar heating variations resulting from Titan's inclined spin axis. The contrast significantly lags the solar forcing, indicating that its production involves the atmosphere well below the unit optical depth level. The contrast has a significant effect on Titan's disk-integrated brightness as seen from earth, and probably accounts for most of the observed long term variation, with solar UV variations accounting for the remainder.
The distribution of pulsars in galactocentric radius and z distance has been determined for opposite halves of the Galaxy, using data on 328 pulsars from three surveys. The distributions in galactocentric radius are found to be significantly different at positive and negative longitudes, although both show strong peaks between 5 and 6 kpc. There is also some indication that pulsars are located preferentially along spiral arms. Distributions in the z component of dispersion measured above and below the galactic plane also show asymmetry, with higher dispersion occurring at negative z. This may imply the existence of a narrow (approximately 100 pc), high electron density layer below the plane of the sun in the inner galaxy.
The April 15 and 28, 1978 solar flares appear to have 0.5-20 MeV protons trapped between a pair of shocks, and the large count rate enhancement observed, along with large ranges of radial distance and longitudinal angles, imply a prolongation of trapping for a period of weeks. The apparent ability of a shock whose plasma signature is faint to confine MeV protons in the outer solar system may have significant implications for cosmic ray studies. Analytical results also imply significant azimuthal asymmetry in plasma and energetic particle behavior, at distances as far as 16 AU from the sun. Combining these observations provides evidence for unexpectedly complex interactions in the outer solar system between energetic particles and solar wind plasma.
The effects of a combined convection and corotation electric field across the Io plasma torus are considered. A dawn-to-dusk electric field E sub C will modify the orbits of charged particles shifting them toward dawn. The radial drift imposed by the perturbed orbits implies a local time-dependent modulation of low-energy ion and electron temperatures with particles hotter at dusk than at dawn. With E sub C approximately 4 mV/m, the orbits near 6 Jupiter radii would be shifted by approximately 0.2 Jupiter radius. Then the electron temperature would be 20% higher at dust than at dawn, an effect which could explain the local time asymmetry of EUV intensity found by the Voyager ultraviolet spectrometer. The source of the convection electric field is internal to the magnetosphere, and is attributed to the tailward escape of Iogenic and Jovian plasma beyond the Alfven surface.
Observational data for Iapetus and other Saturn moons are used to show that the dark areas on Iapetus feature organic chromophores caused by UV irradiation of CH4-rich ice. The Iapetus albedo pattern, brighter at the poles and in the trailing hemisphere, is suggested to originate from ballistic impact redistribution of surface material in terms of an impact flux gradient. The orange/violet color ratios from Voyager imagery were measured as 1.46 for the leading hemisphere and 1.24 for the trailing hemisphere. The evolution of the Iapetus regolith during processes of ice evaporation, impact ablation, material transport, and chemical alteration is discussed for factors causing the albedo asymmetry. Comparisons of surface features of Titan, Oberon,, and Hyperion with those of Iapetus indicate a balance may exist between UV photochemistry and ablation on Iapetus, with the impact gradient having been determined by the tidally locked revolution of the moon. Voyager 2 data on the uranian moons are expected to offer confirmation or denial of the model.
Whether the baryon asymmetry in the universe is a locally varying or universally fixed number is examined with focus on the existence of a possible matter antimatter domain structure in the universe arising from a GUT with spontaneous CP symmetry breaking. Theoretical considerations and observational data and astrophysical tests relating to this fundamental question are reviewed.
An analysis of the diurnal anisotropy on geomagnetically quiet days was performed using neutron monitor data at Deep River, Leeds, Rome and Tokyo, well distributed in latitude and longitude for the period 1964-79. The days were separated according to the polarity of IMF on that day. A significant difference in the amplitude and phase was found on towards and away polarity days, particularly during the years of high solar activity and large north-south asymmetry. These results (particularly time of maximum) on geomagnetically quiet days show some better relationship to the expected results as compared to the results obtained using all the days in a year.
Temkin (1982) has derived the ionization threshold law based on a Coulomb-dipole theory of the ionization process. The present investigation is concerned with a reexamination of several aspects of the Coulomb-dipole threshold law. Attention is given to the energy scale of the logarithmic denominator, the spin-asymmetry parameter, and an estimate of alpha and the energy range of validity of the threshold law, taking into account the result of the two-electron photodetachment experiment conducted by Donahue et al. (1984).
Using the extended boundary condition method, scattering calculations from randomly oriented rotationally symmetric nonspherical particles were made, the size parameters (1-25) and the refractive indicies (1.5 0.02i) of which were chosen to relate to the transfer of solar and IR radiation in an aerosol atmosphere. Comparison of computations for 23 Chebyshev shapes to corresponding size-averaged spherical results revealed that nonsphericity increased absorption for size parameters larger than around 10 and decreased the asymmetry factor, and correspondingly increased the backscattered fraction, in the size ranges 8-15. The scattering efficiency was somewhat larger for nonspherical particles, while the single-scattering albedo tended to be smaller, and concavity was shown to almost always enhance spherical-nonspherical differences.