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  • Organic Chemistry  (714)
  • ENERGY PRODUCTION AND CONVERSION  (634)
  • LUNAR AND PLANETARY EXPLORATION  (601)
  • ASTROPHYSICS  (578)
  • ASTRONOMY  (384)
  • 1995-1999
  • 1980-1984  (2,911)
  • 1950-1954
  • 1981  (2,911)
Collection
Keywords
Publisher
Years
  • 1995-1999
  • 1980-1984  (2,911)
  • 1950-1954
Year
  • 1
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    Curatorial functions and the U.S. Antarctic meteorite program (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: The discovery of concentrations of meteorites in Antarctica by Japanese field parties in 1969, and subsequently by joint U.S.-Japanese and U.S. field parties since 1976 has provided a significant new resource for understanding the origin and evolution of the solar system. The number of meteorites as well as the variety of meteorites has increased dramatically, and substantial amounts of data derived from their study has begun to appear in the scientific literature. The U.S. program of investigation has drawn on curatorial experience derived from the lunar program to: (1) develop specific collection and preliminary examination protocols; (2) provide documented samples for scientific investigations in response to specific requests; and (3) coordinate research by scientific consortia. The productivity of scientific research is significantly enhanced by these management approaches. Some of the results of the curatorial program for Antarctic meteorites carried out over the past three years are described.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: National Institute of Polar Research, Memoirs (ISSN 0386-0744); 20, D
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  • 2
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    Spectroscopy in X-ray astronomy (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: Detailed features in cosmic X-ray sources and their associated temporal variation over a wide energy range were studied. Excess emission and absorption at approximately 6 to 7 kiloelectron volts in the spectra of supernova remnants, binary X-ray sources, and clusters of galaxies were observed. A gas scintillation proportional counter (GSPC) will be used as the detector system. In the gas scintillator the principal limitation is due to the statistics of the initial ionization process only.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 3
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    Far ultraviolet astronomy using the FAUST telescope (1981)
    In:  CASI
    Details
    Publication Date: 2006-06-04
    Description: The Far Ultraviolet Space Telescope (FAUST) a compact, wide field-of-view, far ultraviolet instrument designed for astronomical observations of extended and point sources is discussed. The design and application of the instrument are described. The prime objective is to observe faint astronomical sources with sensitivities higher than previously available. Scientific programs will include: (1) a search for ultraviolet stars which are predicted to exist at the stage of evolution prior to the final death of a star; (2) observations of galaxies and quasars; and (3) joint programs with other Spacelab 1 experiments. The secondary objective is to verify the suitability of the Spacelab as a platform for far ultraviolet astronomy: data will be provided on the ultraviolet background levels due to astronomical, terrestrial, and spacecraft generated sources; the levels of contaminants which affect ultraviolet instruments; and the capability of the Orbiter for stable pointing at celestial sources for useful periods of time.
    Keywords: ASTRONOMY
    Type: NASA. Marshall Space Flight Center Spacelab Mission 1 Expt. Descriptions; 3 p
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  • 4
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    Development of a window protection assembly for a shuttle experiment (1981)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: A window environmental protection assembly developed for the shuttle infrared leeside temperature experiment is described. The assembly consists of a carbon phenolic composite window mount which contains two silicon windows, a fibrous environmental protection plug to protect the windows during launch operations and ascent heating, a release mechanism used to jettison the plug just prior to atmospheric entry, and two pin puller mechanisms which retain the plug. The plug is released from the window mount assemblies using pneumatic pin pullers and separation springs in the release mechanism. The assembly was designed and tested to withstand the severe mechanical and thermal environments which could be experienced at the top of the shuttle orbiter vertical stabilizer during the ascent, on-orbit, and entry periods of the shuttle trajectory.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA. Marshall Space Flight Center The 15th Aerospace Mech. Symp.; p 303-329
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  • 5
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    Comets (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The nature and origin of comets is discussed. Observations of the principal parts of comets, the dust and plasma tails, the hydrogen cloud, the coma and the cometary nucleus, are presented, and the icy conglomerate model of Whipple as extended by Delsemme accounting for the observed properties and their variation with heliocentric distance is examined. The origin of comets is considered in relation to the orbital statistics of the long-period comets and the existence of the Oort cloud on the edge of the solar system, and possible roles for comets in the solar nebula and the evolution of the solar system are indicated. Particular attention is then given to the discovery and properties of Halley's Comet, which is expected to reach perihelion in 1986, and to possible flyby and rendezvous missions to Halley's Comet and others.
    Keywords: ASTRONOMY
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  • 6
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    The Galilean satellites (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The general characteristics of the Galilean satellites, as determined from Voyager data, are described. Attention is then given to the characteristics (surface features, colors, compositions, and geophysical and geochemical processes) of the particular satellites. Particular consideration is given to the nature of Io's atmosphere and to magnetospheric interactions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 7
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    Atmospheres of the terrestrial planets (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The paper reviews current knowledge of the characteristics of atmospheres surrounding the terrestrial planets; attention is given to composition, temperature, characteristics of the upper atmospheres, and meteorology. In addition, the long-term history of the atmospheres is discussed, along with some of the major climatic changes that have occurred. Finally, consideration is given to future efforts that will enhance the understanding of these subjects.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 8
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    On the generation and maintenance of turbulence in the interstellar medium (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The broad spectrum of turbulent motions observed in the interstellar medium may be produced by the shearing action of differential galactic rotation. A steady state eddy distribution is maintained as energy cascades down the eddy hierarchy to smaller-scale motions. The characteristic decay time for interstellar turbulence is found to be 50-billion yr. Objections frequently raised against the presence of long-lived turbulent motions in the interstellar medium are therefore invalid, since these arguments usually presuppose that there is no source of fresh turbulent energy.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 246
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  • 9
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    Electron densities for 10 planetary nebulae derived from the semiforbidden C III lambda 1907/1909 ratio. II (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Electron densities for IC 351, IC 2165, J900, IC 3568, NGC 6644, NGC 6891, IC 4997, NGC 7009, Hu 1-2, and IC 5217 are derived from high-dispersion semiforbidden C III spectrograms. For seven of these nebulae, the derived electron density is larger than the values derived from either surface brightness measurements or forbidden line ratios. Only one object, Hu 1-2, shows pronounced splitting of the semiforbidden C III emission lines due to a large expansion velocity.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 10
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    Near-infrared spectrophotometry of the satellites and rings of Uranus (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: New spectrophotometry from 1.5 to 2.5 microns is reported for the Uranian satellites Titania, Oberon, and Umbriel. A spectrum of the rings of Uranus from 2.0 to 2.4 microns is also reported. No evidence is found for frost covering the surface of the ring material, consistent with the low albedo of the rings previously reported by Nicholson and Jones (1980). The surfaces of the satellites are found to be covered by dirty water frost. Assuming albedos of the frost and gray components covering the Uranian satellites to be the same as the light and dark faces of Iapetus, radii are derived that are roughly twice those inferred from the assumption of a visual albedo of 0.5.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 45; Mar. 198
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  • 11
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    First detection of line emission from the hot interstellar medium with solid state detectors (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously reported enhanced soft X-ray emission from the North-Galactic Polar region supports the theory of a hot interstellar component. This paper reports the first detection of line emission from the hot interstellar component in the North-Galactic-Polar region. Measurements were made with solid state Si(Li) detectors aboard a spin-stabilized rocket launched from the White Sands Missile Range on March 22, 1980. Two features are clearly present in the low energy portion of the spectrum derived from the data. They correspond to emission lines from C V (300 eV) and C VI (360 eV), and from O VII (560 eV) and O VIII (650 eV). The detection of emission lines coming from these highly stripped ions is direct evidence for the thermal origin of the emission and confirms the presence of a hot (1-million K) component in the interstellar medium.
    Keywords: ASTROPHYSICS
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  • 12
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    Medium energy gamma ray astronomy with transpacific balloon flights (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Transpacific balloon flights with the University of California, Riverside (UCR) double scatter telescope are discussed. With flight durations from 5 days up to perhaps 15 days the long observation times necessary for medium energy (1-30 MeV) gamma ray astronomy can be obtained. These flights would be made under the auspices of the Joint U.S.-Japan Balloon Flight Program at NASA. It is proposed that flights can provide at least 30 hours of observation time per flight for many discrete source candidates and 120 hours for detecting low intensity cosmic gamma ray bursts.
    Keywords: ASTRONOMY
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  • 13
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    Temporal and spatial variations observed in the ionospheric composition of Venus - Implication for empirical modelling (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The distributions of several ion species in a data base obtained by in situ measurements of the thermal ion composition of the ionosphere of Venus by the Pioneer Venus Orbiter have been sorted to identify temporal and spatial variations and determine the feasibility of an analytical representation of the experimental results. The first results from the sorting of several prominent ions including O(+), O2(+), and H(+) and several minor ions including CO2(+), C(+), and H2(+) reveal significant diurnal variations which consist of strong day to night contrast in the ion concentrations, with differences of one to two orders of magnitude, depending upon ion mass and altitude. It is suggested that repeatable day to night gradients in the ion distribution are adaptable to parametric modeling.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 14
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    Studies in astronomical time series analysis. I - Modeling random processes in the time domain (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Several random process models in the time domain are defined and discussed. Attention is given to the moving average model, the autoregressive model, and relationships between and combinations of these models. Consideration is then given to methods for investigating pulse structure, procedures of model construction, computational methods, and numerical experiments. A FORTRAN algorithm of time series analysis has been developed which is relatively stable numerically. Results of test cases are given to study the effect of adding noise and of different distributions for the pulse amplitudes. A preliminary analysis of the light curve of the quasar 3C 272 is considered as an example.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series; 45; Jan. 198
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  • 15
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    Three new 'nonterrestrial' molecules (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Eight new interstellar lines have been detected from three molecules not previously observed spectroscopically in space or in the laboratory. One is a linear or nearly linear molecule with microwave constants B0 equals 21,337.15 plus or minus 0.06 MHz, D0 equals 21.4 plus or minus 1.5 kHz. This is the thioformyl ion HCS(plus), first identified because B0 and D0 are close to those calculated, and now confirmed by laboratory detection of one of the present lines (Gudeman et al.). The second molecule, also linear or nearly so, has microwave constants B0 equals 10,691,406 plus or minus 0.043 MHz, D0 equals 1.84 plus or minus 0.91 kHz close to those expected for the isoelectronic systems HOCO(plus) and HOCN; a choice between the two cannot be made on the basis of the available astronomical data. The existence of a third molecule is deduced from an unidentified line at 85,338 MHz that has been found in many sources, is fairly intense in several, and may be self-absorbed in Sgr B2.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 16
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    Effects of gamma-ray, neutrino, and particle production on the energetics and dynamics of compact extragalactic radio sources (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Consideration is given to particle production and high-energy radiation within apparently superluminal radio components of extragalactic radio sources forming within the apparent region of nuclear activity of a quasar or active galaxy. The physical conditions in compact components observed as radio emitters are derived for the quasars 3C 273 and 3C 345 and extrapolated to those of initial components of sizes on the order of 10 to the 15th cm on the basis of two-dimensional relativistic jet and relativistic three-dimensional models of component expansion. Probabilities that a given particle avoids an inelastic collision in the relativistic plasma are calculated for both cases which show that collisions which produce particles and radiation may be very important during the formation of a compact radio component. The consequences of electron-positron production, bremsstrahlung and proton-proton inelastic collisions ultimately giving rise to neutrinos and gamma rays for the development and energetics of the radio component are then examined, and upper limits to the amount of energy which can be channeled into radio components from an active region without giving rise to a high-energy X-ray source are derived.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 245
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  • 17
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    Discovery of phase-locked variable polarization in an RS Canum Venaticorum-like star, HR 5110 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Using measurements on 79 nights in 1980 January-August, it is established that the polarization in the ultraviolet (U band) varies synchronously on the known binary period of 2.6132 days, with a peak-to-peak amplitude of 0.03%. The pattern is mainly second harmonic in character, as typical of binary star examples such as Algol and Upsilon Her. Reflection by the cooler star, by a plasma concentration, or both, is suggested. The scale of the polarization seems to be consistent with Rayleigh scattering by neutral hydrogen on the cooler star, and a roughly lambda to the -4th wavelength dependence should be searched for. The QU curve suggests a sizeable inclination for the system, of about 45 deg, but this is preliminary. Separately, a possible weak periodicity might be present on a subsidiary period, conceivably related to a rotating star spot.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 18
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    Dynamic variations observed in thermal and superthermal ion distributions in the dayside ionosphere of Venus (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In-situ measurements of the ion composition and concentration of the ionosphere of Venus are obtained with the Bennett RF ion mass spectrometer (OIMS) on the Pioneer Venus Orbiter (PVO). Dayside ion profiles exhibit considerable variability in the height of the ionopause as well as the scale heights of the ion constituents, which reflect the compression and expansion of the ionosphere in response to solar wind variations. Near the dayside upper boundary of the thermal O+ distribution, super-thermal ions are detected by the OIMS, presenting a complication for identifying the ion signature of the ionopause. Correlated with the presence of the superthermal ions, the ac electric field detector (OEFD) detects regions of intensified signals, with peak response in the 100 Hz frequency channel. It is expected that further analysis of the superthermal ion-electric field signatures will contribute to a clearer understanding of the physical processes underlying the formation of the ionopause.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 19
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    The electrodynamic interaction of Io with Jovian magnetosphere (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 20
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    The 45 micron H2O ice band in the Kleinmann-Low Nebula (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 245
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  • 21
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    Bidirectional reflectance spectroscopy. II - Experiments and observations (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Aspects of the theoretical bidirectional reflectance expression derived by Hapke (1981) are studied experimentally, and it is shown that the expression describes satisfactorily the measured angular scattering and spectral properties of a cobalt glass powder in which the two properties vary greatly with wavelength. The theoretical reflectance function also describes measured distributions of intensity across the surfaces of planets, except near the sunlit limb, where the macroscopic roughness influences the brightness.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Apr. 10
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  • 22
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    Transport velocity transformation - A convenient method for performance analysis of multilayer solar cell structure (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is noted that in the case of low-level injection, space-charge quasi-neutrality, and spatially constant material parameters (including an electrostatic field), the individual layer can be treated analytically and the basic solar cell performance parameters can be evaluated from three equations. The first equation represents the transformation of the transport velocity across the layer from the other layer boundary. The second establishes the light-generated current output from the layer interface, under the influence of the transport velocities and minority-carrier density at both layer boundaries and of bulk recombination. The third equation describes the flow of these carriers across other layers. The power of the approach is considered to lie in its facility for analysis of the solar cell's performance layer by layer, giving a clear picture of the individual layer's influence on cell efficiency.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: IEEE Transactions on Electron Devices; ED-28; May 1981
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  • 23
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    An 81 minute modulation of the X-ray flux from 2A 0311-227 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is demonstrated that the X-ray flux from 2A 0311-227 is modulated at the 81 minute orbital period of its optical counterpart. An absorption dip with N sub H approximately equal to 5 x 10 to the 22nd H atoms per sq cm is observed at magnetic phase 0.42 that is interpreted as the accretion column of a magnetic white dwarf passing in front of the X-ray source. The spectrum is thermal with a temperature of 18 keV and a 300 eV equivalent-width iron line at 6.6 keV.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 24
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    Concerning the Wolf-Rayet and other luminous early-type stars (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Effective temperatures, radii, and luminosities were determined from S2/68, ANS, UBV, and uvby photometry for four B0/B1 supergiants, four O4 stars, and four WN7/WN8 stars as well as for four test stars having spectral types between B1.5 V and 09 V and five stars with known angular diameters and effective temperatures. The effective temperatures of B1 Ia+ stars are found to be near 17,000 K, those of O4 stars near 45,000, and those of WN7/WN8 stars near 26,000 K. The question of modeling the atmospheres of hot luminous stars is examined, and it is noted that the photosphere can be modeled adequately using a classical plane-parallel layer model atmosphere. In addition, it is found that the Wolf-Rayet stars of types WN7/WN8 fall in the H-R diagram near the B0 Ia stars, while the others fall near B0.5 III stars. The evolutionary relationship between the Wolf-Rayet and O stars is considered; it is suggested that a Wolf-Rayet spectrum is a short-lived phase in the life of a massive star.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 25
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    Observation of the core of the Perseus cluster with the Einstein solid state spectrometer - Cooling gas and elemental abundances (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Solid State Spectrometer observations of the core of the Perseus cluster have resulted in the detection of X-ray emission lines due to Si, S, and Fe. Analysis of the spectrum indicates that the X-ray emission has at least two characteristic temperatures. This is interpreted in the framework of radiative accretion in the core of the cluster. The derived parameters are a cooling time less than or approximately equal to 2 x 10 to the ninth years for the low-temperature gas, a mass accretion rate of approximately 300 solar masses per year, and a characteristic size of 10-20 kpc for the cool gas. The Fe abundance in the core (approximately 0.4) is similar to the Fe abundance averaged over the whole cluster, indicating that Fe emission is not strongly concentrated about NGC 1275. The Si and S abundances are consistent with solar values.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 26
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    Non-linear stability around the triangular libration points (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The configuration space around the triangular libration points in the Earth-Moon system is partitioned according to the stability of the motion. The regions around L4 and L5 are established where particles placed with zero initial velocity will librate. The complexity of the partitioning is revealed.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 23; Mar. 198
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  • 27
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    Observations of Martian tides over two annual cycles (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The first four diurnal surface pressure harmonics have been analyzed over major portions of two Martian annual cycles (Mars years) at the two Viking lander sites. The diurnal harmonics of surface wind have also been analyzed at one of the sites. Since the atmospheric tides have previously been shown to provide a good indication of Martian global dust storms, these results provide a basis for comparing dust storm activity in the two years. Two global dust storms occurred during the first year. During the second year, there was only one major storm, and it closely followed the pattern of the first storm of the first year. A significant feature of the results is the brief, but nearly complete, vanishing of the diurnal pressure tide at the onset of one of the global dust storms. It is proposed that this may have been due to interference between the normal westward-propagating diurnal tide and a topographically forced eastward propagating tide, and that the latter may have helped initiate the global storm.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 38; Jan. 198
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  • 28
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    A Martian general circulation experiment with large topography (1981)
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    Publication Date: 2011-08-18
    Description: A three-layer general circulation model of the Martian atmosphere is described, and the assumptions governing the model are discussed. The simulated, zonally averaged circulation is found to have only limited sensitivity to differences between this model and an earlier general circulation model; this circulation compares reasonably well with observations. It is also found that the meridional mass flow produced by the seasonal condensation of CO2 in the winter polar region has a major influence on the circulation; owing to the weak influence of atmospheric heat transport, however, the mass flow is governed almost entirely by radiation. Quasi-barotropic stationary waves, which are forced kinematically by the topography and which resemble topographically forced terrestrial planetary waves, are generated by the model in the winter hemisphere region of strong eastward flow, while baroclinic stationary waves are thermally forced by topography in the tropics and summer subtropics. It is also concluded that transient baroclinically unstable waves, of somewhat lower dominant wavenumber than those found on the earth, are generated in winter midlatitudes; their amplitudes, wavenumbers, and phase speeds closely agree with what has been deduced from the Viking lander observations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences; 38; Jan. 198
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  • 29
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    Meteoric ion production near Jupiter (1981)
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    Publication Date: 2011-08-18
    Description: Meteoric ion layer formation within the Jovian atmosphere is examined with attention to metallic ion production in the lower ionosphere. The Fe(+) impact ionization rate within the Jovian atmosphere peaks above the mesopause with a magnitude of approximately 0.5 cu cm/sec and is much less than the ambient ionosphere photoionization rates near the late afternoon Pioneer 10 ionosphere occultation. Charge exchange of the ablated neutral Fe atoms with ambient ions can result in an Fe(+) production rate of about 10 cu cm/sec. Ignoring transport, steady state Fe(+) density maxima of about 10,000 or 1,000,000 cu cm can be maintained when Fe(+) loss is through radiative association or radiative recombination respectively. Even if an estimated lower limit to the incident meteoroid flux is used based on a meteoroid spatial density which does not vary with distance from the sun, the corresponding Fe(+) peak densities are 1,000 and 500,000 cu cm, respectively. Meteoric ion densities may thus be important in the Jovian lower ionosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Mar. 1
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    Discovery of natural gain amplification in the 10-micrometer carbon dioxide laser bands on Mars - A natural laser (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Fully resolved intensity profiles of various lines in the carbon dioxide band at 10.4 micrometers have been measured on Mars with an infrared heterodyne spectrometer. Analysis of the line shapes shows that the Mars atmosphere exhibits positive gain in these lines. The detection of natural optical gain amplification enables identification of these lines as a definite natural laser.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 212; Apr. 3
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  • 31
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    High-resolution observations of the QSO 3C 345 at 1.3 centimeters (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High-resolution VLBI observations made at a frequency of 22.235 GHz of the quasar 3C 345 are discussed. Antennas located at the Crimean Astrophysical Observatory, USSR; Onsala, Sweden; Effelsberg, West Germany; and the Haystack Observatory, Massachusetts were employed at 4-min integration times to provide baselines ranging up to 5.5 x 10 to the 8th wavelengths. About 40% of the total flux density of 7.85 Jy, observed in November 1977, and 8.05 Jy, observed in October 1978, is found to originate in an unresolved component of the quasar core in a region less than 0.1 milliarcsec in diameter. The elongated jet-like component of the quasar is observed to contain several peaks of emission extending up to 6 milliarsec from the core which decreased in extent between the two observations.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 243
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  • 32
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    Radio astronomy (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The activities of the Deep Space Network in support of radio astronomy operations during the first quarter of 1981 are reported. Results of the use of a low noise maser are presented, as well as updates in DSN support of experiments sanctioned by the Radio Astronomy Experiment Selection Panel.
    Keywords: ASTRONOMY
    Type: The Telecommun. and Data Acquisition Rept.; p 1-2
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  • 33
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    Solar flare theory (1981)
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    Publication Date: 2011-08-18
    Description: Solar flare models are briefly reviewed with emphasis on the physical mechanisms invoked to explain the flare. The physics of each mechanism and their interrelations are discussed in detail. Mechanisms are classified by their drivers (the source of energy on which they feed). The application of these mechanisms to coronal heating is evaluated.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 413-470
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  • 34
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    Heating and acceleration of the solar wind (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The dynamics of the expanding corona are discussed emphasizing the physical processes which accelerate the plasma as it flows away from the Sun. The solar wind plays a dominant role in the energy balance of the part of the corona in which it originates. The wind acceleration processes, in large part, with the mechanisms that transport energy to the corona in the first place.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 373-384
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  • 35
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    Oscillations and pulsations (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A theory to describe the observed photospheric 5 minute oscillations, chromospheric 3 minute oscillations, and possible motions of the interior with periods ranging from 40 to 160 minutes is discussed. It is similar to the theory of nonradial stellar oscillations developed to describe the low angluar order modes (one or two wavelengths around a circumference); however, the solar oscillations have thousands of wavelengths around a circumference. The properties of waves in stars, their restoring forces, periods and wavelengths, and their propagation and motions are discussed.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 263-287
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  • 36
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    Earthquakes - on the moon (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Information obtained with the Apollo lunar seismic stations is discussed. The four types of natural seismic sources that have been identified are described, viz., thermal moonquakes, deep moonquakes, meteoroid impacts, and shallow moonquakes. It is suggested that: (1) the thermal quakes represent the slow cracking and movement of surface rocks; (2) the deep quakes are induced by the tide-generating force of the earth's gravity; (3) the meteoroids responsible for most of the observed impacts are in the mass range from 1 to 100 kg and are clustered in groups near the earth's orbit; and (4) the shallow quakes are similar to intraplate earthquakes and indicate that the moon is as seismically active as the interior regions of the earth's tectonic plates. The structure of the lunar interior as inferred from seismic signals due to both the last three natural sources and 'artificial' impacts of used spacecraft is examined in detail.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Discovery; 6; 1, 19; 1981
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  • 37
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    Solar cell measurements (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The measurement of the electrical performance characteristics of individual solar cells is discussed. One of the reasons is determination of the output power, measurement of the effect of various degradation mechanisms, and separation of cells by current and voltage for eventual use in series and parallel combinations. Major problem areas in making accurate performance measurements are the determination of the irradiance level during measurement, the measurement and control of cell junction temperature, and the contacting of the separate current and potential leads to the cell under test. Solar cells respond to only part of the solar spectrum, irradiance measurement made with blackbody detectors lead to spectral mismatch errors. The use of reference cells with a spectral response similar to that of the test cell reduces this error. Reference cells are calibrated at standard atmospheric conditions with all cells calibrated at the same conditions.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Midwest Research Inst. Com. Photovoltaics Meas. Workshop Proc.; p 227-233
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  • 38
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    High-resolution IUE observations of the 1981 eclipse of 32 CYG (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: 32 Cyg shows a spectacular pure emission line spectrum during eclipse. Six weeks later, most lines, which were observed in emission during eclipse, are seen as P Cygni type profiles with strong absorption components. The lines are formed through line scattering of B star light in the extended atmosphere (wind) of the K supergiant. During eclipse, the emission parts of the P Cyg lines remain visible since the size of the line scattering sphere around the B star is larger than the red giant. Other emission lines are formed in a shock front near the B star (CIV, SiIV, FeIII) and possibly in an accretion disk. The strong FeII UV Mult. 191 lambda lambda 1785-88 A is shown to be formed through optical pumping via FeII UV Mult. 9 photons. The phase dependence of the P Cyg type profiles is modelled by means of line transfer calculations in nonspherical, 3-dimensional geometry with velocity fields.
    Keywords: ASTRONOMY
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 245-259
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  • 39
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    A comparison of circumstellar gas and dust in M giants and supergiants (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This paper presents the results of a study of circumstellar gas and dust in a larger sample of stars than that of Hagen (1978). The gas-to-dust ratio varies considerably from star to star. The observations were obtained at Cerro Tololo Interamerican Observatory and Kitt Peak National Observatory. CS gas was observed with 2.5 and 5.1 A/mm echelle spectra obtained with the 4-meter telescopes. CS dust was observed through infrared photometry done with the CTIO 60 and KPNO 50 telescopes.
    Keywords: ASTROPHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 231-238
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  • 40
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    Convective dynamos for rotating stars (1981)
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    Publication Date: 2011-08-18
    Description: Global dynamo theory is applied to the problem of why some stars have field reversing dynamos, and others do not. It is argued that convectively driven dynamos are the most likely source of magnetic fields in stars that have convection zones.
    Keywords: ASTROPHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 165-179
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  • 41
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    Shock waves, atmospheric structure and mass loss in Miras (1981)
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    Publication Date: 2011-08-18
    Description: Large amplitude shock waves are observed to be present in the atmospheres of the Mira variables: spectral line doubling with Delta v 30 km/s is present in infrared spectra. Even the visible spectra contain some evidence for such shocks. These shocks are sufficiently large to clearly dominate the energy balance of the atmosphere. Mira variables also show symptoms of substantial mass loss rates: they are strong maser and infrared continuum sources and have strong circumstellar absorption features. The pulsation induced shocks which are seen to be present are obvious suspects for causing or enhancing the mass loss from these stars. The Miras thus present an ideal case for the study of dynamical effects on atmospheric structure, since both the dynamics and the results are clearly observable. The results are given of calculations of the thermalization and cooling of the shock heated material passing through shock fronts whose properties were selected to be consistent with both the isothermal models and the spectroscopic observations.
    Keywords: ASTROPHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 147-151
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  • 42
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    Evidence for extended chromospheres surrounding red giant stars (1981)
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    Publication Date: 2011-08-18
    Description: There is now an increasing amount of both observational evidence and theoretical arguments that regions of partially ionized hydrogen extending several stellar radii are an important feature of red giant and supergiant stars. This evidence is discussed and the implications of the existence of extended chromospheres in terms of the nature of the outer atmospheres of, and mass loss from, cool stars are examined.
    Keywords: ASTROPHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 137-145
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  • 43
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    Momentum and energy balance in late-type stellar winds (1981)
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    Publication Date: 2011-08-18
    Description: Observations at ultraviolet and X-ray wavelengths indicate that the classical picture of a static stellar atmosphere containing a radiative equilibrium temperature distribution is inapplicable to the majority of late type stars. Mass loss and the presence of atmospheric regions characterized by gas temperatures in excess of the stellar effective temperature appear to be almost ubiquitous throughout the HR diagram. Evidence pertaining to the thermal and dynamical structure of the outer envelopes of cool stars is summarized. These results are compared with the predictions of several theoretical models which were proposed to account for mass loss from latetype stars. Models in which the outflow is thermally radiatively, or wave driven are considered for identification of the physical processes responsible for the observed wind properties. The observed variation of both the wind, thermal and dynamical structure as one proceeds from the supergiant branch toward the main sequence in the cool portion of the HR diagram give consideration to potential mechanisms for heating and cooling the flow from low gravity stars.
    Keywords: ASTROPHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 83-97
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  • 44
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    A heating mechanism for the chromospheres of M dwarf stars (1981)
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    Publication Date: 2011-08-18
    Description: The atmospheric structure of the dwarf M-stars which is especially important to the general field of stellar chromospheres and coronae was investigated. The M-dwarf stars constitute a class of objects for which the discrepancy between the predictions of the acoustic wave chromospheric/coronal heating hypothesis and the observations is most vivid. It is assumed that they represent a class of stars where alternative atmospheric heating mechanisms, presumably magnetically related, are most clearly manifested. Ascertainment of the validity of a hypothesis to account for the origin of the chromospheric and transition region line emission in M-dwarf stars is proposed.
    Keywords: ASTROPHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 73-79
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  • 45
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    The generation of acoustic energy from stellar convection zones (1981)
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    Publication Date: 2011-08-18
    Description: The heating of stellar chromospheres and coronae by the dissipation of acoustic waves is an important heating mechanism. It is only in the lower solar chromosphere that short period acoustic wave heating seems undisputed. The arguments leading to the rejection of the so called acoustic heating theory are derived from comparisons of calculated acoustic energy fluxes with observational or theoretical requirements.
    Keywords: ASTROPHYSICS
    Type: Smithsonian Astrophysics Observatory 2nd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Vol. 1; p 67-72
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  • 46
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    The atmosphere and ionosphere of Jupiter (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The thermal structure of the upper atmosphere of Jupiter, the composition of the atmosphere and the strength of mechanical mixing, and sources and sinks of ionization in the Jupiter ionosphere are described from Voyager UV spectrometer, radio, IR, and imaging data. A topside ionospheric temperature of 1300 K was observed, along with an energy equilibrium between the plasma and neutral gas in the upper atmosphere. A composite thermal structure is provided, noting a close similarity to earth conditions at upper levels, and enhanced thermal behavior has been detected between the times of solar minimum and maximum activity. Ammonia photochemistry is examined, and measured concentrations of H2, CH4, C2H6, and C2H2 as a function of height are outlined. Eddy diffusion coefficient calculations are carried out, yielding a highest Ly-alpha intensity of 100 million sq cm/sec. The increased exospheric temperature between 1973 and 1980 is stressed to have no known satisfactory explanation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Vistas in Astronomy; 25; pt. 3
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  • 47
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    On the formation of protostellar disks (1981)
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    Publication Date: 2011-08-18
    Description: An analysis is presented of the hydrodynamic aspects of the growth of protostellar disks from the accretion of a rotating gas cloud. Streamline equations for the flow onto the disk are derived, including the special case where the disk is very thin. For the radial structure of the disk, detailed equations of conservation of mass, momentum, angular momentum, and energy are given. Exact solutions are found for the case of no internal viscosity. For the more general case where there is viscous stress, hypotheses are formulated with the objective of discovering the main qualitative characteristics of a turbulent system and to estimate the magnitude of the turbulent stress. Solutions are also found for boundary conditions, and the large and small viscosity limits. The relation of energy balance to disk thermal structure is detailed. Finally, trends in the collapse of the dust cloud are discussed in the light of the solutions given.
    Keywords: ASTROPHYSICS
    Type: Icarus; 48; Dec. 198
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  • 48
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    The 1979-1980 eclipse of Zeta Aurigae. II - The emission spectrum (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: UV observations using the IUE are employed to discuss the strength and changes of Zeta Aur between a second contact and mid-eclipse in 1979, the relative visibility of the supergiant's chromosphere as compared with the circumstellar (CS) nebular scattering of the B star photons, and the origin of the high speed CS components observed at all orbital phases. Agreement has been found for a spectoscopic radius of 200 solar radii and a 400 pc distance, and eclipse emission lines were recorded from 1238.9-2802.7 microns. An asymmetry in the Fe III lines at 46 plus or minus 15 km/sec was seen during eclipse and is taken to indicate downflowing material. The high speed wind flowing from the K supergiant is thought to expand homogeneously until encountering the B type main sequence star, where an accretion bow shock forms, and the smaller star's passage near the K star at periastron may cause local surface heating and subsequent high speed flows.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
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  • 49
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    Optical photometry of SS 433 - 200 nights of data 1979-1980 (1981)
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    Publication Date: 2011-08-18
    Description: Results from over 200 nights of optical photoelectric photometry of SS 433 during the period July 1979-October 1980 are presented. The data, taken in unfiltered light, the V band, an interference filter band centered on stationary H-alpha and a far-red band, provide evidence for an underlying 164-day light variation of peak-to-peak amplitudes 0.50 magnitude in V and 0.7 magnitude at 6567 A, and a binary-like variation with period 13.074 days and peak-to-peak amplitudes 0.50 and 0.60 magnitudes, respectively. The 13-day light curves are found to change slightly as a function of phase in the 164-day cycle, while seemingly erratic light fluctuations of up to 1 magnitude in 1 day and about 2 magnitudes in 3-4 days are imposed on both cyclic variations. It is noted that a conventional close-binary model is incapable of accounting for all the observed features, and alternatives involving some sort of luminous, rapidly changing extended low-mass envelope or screen in the binary system must be sought.
    Keywords: ASTRONOMY
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  • 50
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    Hard X-ray structure of the Crab Nebula (1981)
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    Publication Date: 2011-08-18
    Description: Two-dimensional maps of the Crab Nebula have been synthesized in 22-64 keV range through the modulation collimator experiment. The effective angular resolution is about 15-arcmin. The result indicates that the Crab morphology is strictly controlled by the pulsar.
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    Martian channels and valleys - Their characteristics, distribution, and age (1981)
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    Publication Date: 2011-08-18
    Description: The distribution and ages of Martian channels and valleys, which are generally believed to have been cut by running water, are examined with particular emphasis on the small branching networks referred to as runoff channels or valley networks. Valleys at latitudes from 65 deg S to 65 deg N were surveyed on Viking images at resolutions between 125 and 300 m. Almost all of the valleys are found in the old cratered terrain, in areas characterized by high elevations, low albedos and low violet/red ratios. The networks are deduced to have formed early in the history of the planet, with a formation rate declining rapidly shortly after the decline of the cratering rate 3.9 billion years ago. Two types of outflow channels are distinguished: unconfined, in which broad swaths of terrain are scoured, and confined, in which flow is restricted to discrete channels. Both types start at local sources, and have formed episodically throughout Martian history. Fretted channels, found mainly in two latitude belts characterized by relatively rapid erosion along escarpments, are explained by the lateral enlargement of other channels by mass wasting.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 48; Oct. 198
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    Cosmic ray antiprotons in the closed galaxy model (1981)
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    Publication Date: 2011-08-18
    Description: A calculation is made of the flux of secondary antiprotons expected for the leaky box model and for the closed galaxy model of Peters and Westergaard (1977). The antiproton/proton ratio observed at several GeV is a factor of 4 higher than the prediction for the leaky box model but is consistent with that predicted for the closed galaxy model. It is found that new low-energy data are not consistent with either model. Attention is given to the possibility of a primary antiproton component.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
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  • 53
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    The asymmetric 4.8 hour X-ray modulation of Cygnus X-3 - Model light curves and inferred orbital parameters (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The 4.8 hour X-ray light curve of Cygnus X-3 is quantitatively described by several proposed models under the assumption that the binary orbit of Cyg X-3 is elliptic. The cocoon model implies an apparent size for the X-ray star's companion, which is larger than that of its critical lobe, and it is suggested that the emission of a dense stellar wind by the companion could lead to such a situation. It is shown that a helium star, with or without a hydrogen-rich envelope, seems to be the most likely Cyg X-3 companion, and that some of the observed variations in the 4.8 hour period can be accounted for by the apparent period variations due to apsidal motion.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
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  • 54
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    Infrared photometry of comets Bowell and P/Stephan-Oterma (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Broadband IR photometry in the 1-20 micron range of the comets P/Stephan-Oterma and Bowell shows JHK colors similar to P/Meier and P/Tuttle, which are compatible with the scattering of sunlight by micron-sized grains. In addition, the P/Stephan-Oterma thermal emission was found to have an effective temperature higher than that expected from a blackbody in equilibrium. It is demonstrated that the thermal emission can be fit by models of the dust coma consisting of micron-sized grains, and that most of the flux at all observed wavelengths comes from the dust grains rather than the nucleus.
    Keywords: ASTRONOMY
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  • 55
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    Venus nightside ionospheric holes - The signatures of parallel electric field acceleration regions (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Attention is given to the existence of 'holes', that is, regions of density depletion in the nightside Venus ionosphere associated with regions of radial magnetic fields. The properties of the electrons within the core of these holes are thought to suggest an acceleration process along the magnetic field lines, a process also suggested by the Venera 9 and 10 observations of energetic ions in the Venus tail. On the basis of the observational information, these Venusian plasma depletions are attributed to the presence of parallel electric fields similar to those observed in the terrestrial auroral ionosphere. The resulting electric field accelerates electrons down the field lines, heating the depleted thermal electron population within the hole and producing ionization below the hole. At the same time, ionospheric ions are accelerated outward toward the plasmasheet.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 8; Dec. 198
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  • 56
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    Millimeter-wave experiments for cometary space missions (1981)
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    Publication Date: 2011-08-18
    Description: Predicted brightness temperatures, computed by means of radiative transfer techniques adapted from the modeling of terrestrial ice and snow fields, are given for cometary nucleus models consisting of homogeneous layers of water ice and refractory grain mixtures presented as functions of wavelength. The computed millimeter-wave spectra are sensitive to the values of such physically significant nucleus parameters as (1) crust thickness, (2) subsurface temperature gradient, and (3) sublimating surface boundary temperature. Although antenna beam dilution is a major obstacle for ground-based molecular spectral line radio observations of comets, a millimeter-wave radiometer in the vicinity of the comet would be immune to this effect and able to make observations of several candidate parent molecules in the gas phase.
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  • 57
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    Far-UV, visible, and near-IR reflectance spectra of frosts of H2O, CO2, NH3 and SO2 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Measurements in the 0.1-2.5 micron range are presented for the reflectance spectra of the frosts of several volatiles pertinent to the study of comet nuclei. The frost spectra have distinctive features permitting their identification by spectroscopic reflectance remote sensing, notably in the far UV. It is found that: (1) H2O has a minimum at 0.16 microns and a maximum at 0.13 microns; (2) CO2 has minima near 0.21, 0.18 and 0.125 microns, with maxima at 0.19, 0.135 and 0.120 microns; (3) NH3 is bright at wavelengths longer than 0.21 microns, where reflectance drops to a value of only a few per cent at shorter wavelengths; (4) SO2 has a sharp drop at 0.32 microns, with a minimum at 0.18 microns and a maximum at 0.13 microns. The features in the frost spectra largely correspond to absorption line bands in the gas phase.
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    Collapse and fragmentation of rotating, adiabatic clouds (1981)
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    Publication Date: 2011-08-18
    Description: A numerical hydrodynamics code has been used to calculate the collapse of rotating, adiabatic clouds. The three-dimensional nature of the calculation allows the clouds to fragment in the dynamic collapse phase. Clouds with adiabatic exponent of 7/5 and initial cos(2 phi) density variations fragment into binary systems if the initial ratio of thermal to gravitational energy is small (about 0.05). Clouds with higher thermal energy, however, damp the density variation and form near-equilibrium ellipsoids, with ratios of rotational to gravitational energy less than the critical value for dynamic growth of nonaxisymmetry in Maclaurin spheroids. Even with an adiabatic pressure law, dynamic fragmentation of a collapsing cloud is possible, implying for star formation theory that the low thermal energy fragments produced in isothermal collapse calculations may undergo a subsequent dynamic fragmentation in the nonisothermal regime.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 250
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  • 59
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    Fresnel zone structure in planetary occultations (1981)
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    Publication Date: 2011-08-18
    Description: The structures of the Fresnel zones of an occulting body with a substantial atmosphere are analyzed. The first Fresnel zone is defined as the set of all contiguous points connected to the transmitter and receiver via paths with a combined length within one half wavelength of the stationary value, and calculated by the application of the Huygens-Fresnel principle to a wave front frozen in time as it traverses the region of interest, taking into account wave front curvature of waves undergoing refraction. Calculations of the Fresnel zones of a planet determined by the meeting of wave fronts represented as tori reveal that the zone along the propagation path traversing the nearest portion of the limb to the transmitter has a shape similar to an ellipse, while that of the far zone resembles the letter X. The phase delay along the farside path is found to be a stationary point rather than a minimum, since delay is distributed in the form of a hyperbolic paraboloid near the ray and in the form of a torus intersection for greater separations. Examples are presented for S band propagation deep in the atmospheres of Venus and Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Radio Science; 16; Nov
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  • 60
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    X-ray and VLBI radio observations of the quasars NRAO 140 and NRAO 530 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Einstein X-ray Observatory has confirmed the HEAO 1 detection of the NRAO 140 and NRAO 530 quasars, and found that the low-energy X-ray flux of NRAO 140 is consistent with the high-energy results from the earlier satellite. It is also determined that the X-ray emission from NRAO 530 has either decreased by an order of magnitude, from 1978.0 to 1979.7, or the HEAO 1 field contained a second bright source. The two sources have been observed at 2.8 cm, using a four-station intercontinental VLB array, to find whether the X-ray emission is caused by Compton scattering within the radio components. Dissection of the NRAO 140 into its separate components shows radio parameters that imply a 'Compton problem', in that X-ray emission three orders of magnitude greater than that observed is predicted in one of the components if the source is static. Because the effect is independent of distance, relativistic motion with a Lorentz factor greater than about 40 is required to bring the predicted X-ray flux down to the observed value.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 249
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  • 61
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    Topography of Venus and earth - A test for the presence of plate tectonics (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Comparisons of earth and Venus topography by use of Pioneer/Venus radar altimetry are examined. Approximately 93% of the Venus surface has been mapped with a horizontal resolution of 200 km and a vertical resolution of 200 m. Tectonic troughs have been indicated in plains regions which cover 65% of Venus, and hypsometric comparisons between the two planets' elevation distributions revealed that while the earth has a bimodal height distribution, Venus displays a unimodal configuration, with 60% of the planet surface within 500 m of the modal planet radius. The effects of mapping the earth at the same resolution as the Venus observations were explored. Continents and oceans were apparent, and although folded mountains appeared as high spots, no indications of tectonic activity were discernible. A NASA Venus Orbiting Imaging radar is outlined, which is designed to detect volcanoes, folded mountain ranges, craters, and faults, and thereby allow definition of possible plate-tectonic activity on Venus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: American Scientist; 69; Nov
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  • 62
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    Very high resolution observations of SS433 at 10.65 GHz (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of SS433 made on June 12, 1979, from West Germany, Massachusetts, and West Virginia are discussed. It is noted that SS433 did not show fringes on any baseline although all the calibration sources were seen at their expected strengths. The measured total flux density of SS433 was found to be approximately 0.5 Jy, consistent with previous observations. The source was observed by on-offs at each telescope, which indicates that they were all pointed properly during the observations. The absence of fringes is not attributed to poor observing conditions or instrumental difficulties. It is concluded that if all the 10.65 GHz radiation emanates from a single component, then that component is at least 0.005 arcsec (approximately 10 to the 14th cm) in size. The measurements made on more sensitive intercontinental baselines indicate that there is no component of SS433 smaller than 0.001 arcsec emitting 10.65 GHz radiation above a level of 50 mJy.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 98; 1, Ma; May 1981
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  • 63
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    de Sitter's model and luminosity - Distance in cosmology (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The behavior of luminosity-distance with redshift is analyzed within the framework of homogeneous zero-pressure relativistic cosmology. de Sitter's model is shown to have the most redshift sensitive luminosity-distance function of all cosmologies which have q sub 0 not less than -1. Quasar data which suggest a cut-off in absolute luminosity are reanalyzed and the cut-off disappears if either de Sitter's model or the assumption L(L-alpha) = 3 L(H-beta) is used.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 195
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  • 64
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    Observations of Saturn in the 5- to 8-micron spectral region (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A spectrum of Saturn obtained from the Kuiper Airborne Observatory exhibits an emission peak at 6.8 microns attributed to ethane, but is otherwise dominated by absorption from 5.3 to 7.2 microns. While the large absorption in this spectral region is consistent with the presence of ammonia gas or ammonia ice, or both, such an explanation is inconsistent with the lack of a major absorption near 3.0 microns.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus; 45; Mar. 198
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  • 65
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    Fine-scale characteristics of interplanetary sector boundaries (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The study examines the structure of the interplanetary sector boundaries observed by Helios 1 within sector transition regions during the time interval from December 1974 to April 1975. The transition regions are found to be complex in character, consisting of intermediate average field orientations in some cases as well as a number of large-angle directional discontinuities (DDs). It is suggested that the observed DDs represent multiple traversals of the global heliospheric current sheet caused by local fluctuations in the position of the sheet. There is evidence that such fluctuations are sometimes produced by wavelike motions or surface corrugations of scale length 0.05-0.1 AU, superimposed on the large-scale structure.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 86; May 1
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  • 66
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    Observations of SMC X-1 with the monitor proportional counter on the Einstein /HEAO 2/ X-ray Observatory - The pulse period and its history (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The results of the sixth determination of the pulse period of the X-ray source SMC X-1 are presented. The observations were made in April 1979. The pulse period at this epoch was found to be (0.713683 + or - 0.000032) s referred to phase zero of the binary motion. This result together with all available historical data is utilized to quantify the observed trend toward spin-up. It is found that simple secular trends are not applicable. This finding is interpreted as evidence for additional variations in the pulse period. The obtained results are discussed in the context of present theoretical models for period variations in the binary pulsating X-ray sources. The apparent absence of spin-down episodes in the period history of SMC X-1 is also considered.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 67
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    Two-component X-ray emission from RS Canum Venaticorum binaries (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A summary is presented of results from the Solid State Spectrometer on the Einstein Observatory for seven RS CVn binaries. The spectra of all require two emission components, evidenced by line emission characteristics of plasma at 4-million to 8-million K and bremsstrahlung characteristic of 20-million to 100-million K. The data are interpreted in terms of magnetic coronal loops similar to those seen on the sun, although with different characteristic parameters. The emission regions could be defined by separate magnetic structures. For pressures less than 10 dynes/sq cm the low temperature plasma would be confined within the stellar radii, while the high temperature plasma would, for the synchronous, close binaries, fill the binary orbits. However, for loop pressures exceeding 100 dynes sq cm, the high temperature components would also be confined to within the stellar radii, in loops covering only small fractions of the stellar surfaces. While the radio properties and the occurrence of X-ray flares suggest the larger emission regions, the observations of time variations leave the ambiguity unresolved.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 246
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  • 68
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    Pulsar gamma-rays - Spectra, luminosities, and efficiencies (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The general characteristics of pulsar gamma-ray spectra are presented for a model in which the gamma rays are produced by curvature radiation from energetic particles above the polar cap and attenuated by pair production. It is found that the shape of the spectrum depends on pulsar period, magnetic field strength, and primary particle energy. Comparing numerically calculated spectra with the observed spectra of the Crab and Vela pulsars, it is determined that primary particles must be accelerated to energies of approximately 3 x 10 to the 7th m c-squared. A general formula is determined for pulsar gamma-ray luminosity; it is found to depend on period and field strength.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 245
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  • 69
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    Martian ages (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Four discussions are conducted: (1) the methodology of relative age determination by impact crater statistics, (2) a comparison of proposed Martian impact chronologies for the determination of absolute ages from crater frequencies, (3) a report on work dating Martian volcanoes and erosional features by impact crater statistics, and (4) an attempt to understand the main features of Martian history through a synthesis of crater frequency data. Two cratering chronology models are presented and used for inference of absolute ages from crater frequency data, and it is shown that the interpretation of all data available and tractable by the methodology presented leads to a global Martian geological history that is characterized by two epochs of activity. It is concluded that Mars is an ancient planet with respect to its surface features.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Apr. 10
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  • 70
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    The Uranus occultation of 10 June 1979. I - The rings (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 86; Apr. 198
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  • 71
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    Bidirectional reflectance spectroscopy. I - Theory (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An approximate analytic solution is derived for the radiative transfer equation describing particulate surface light scattering, taking into account multiple scattering and mutual shadowing. Analytical expressions for the following quantities are found: bidirectional reflectance, radiance coefficient and factor, the normal, Bond, hemispherical, and physical albedos, integral phase function and phase integral, and limb-darkening profile. Scattering functions for mixtures can be calculated, as well as corrections for comparisons of experimental transmission or reflection spectra with observational planetary spectra. The theory should be useful for the interpretation of reflectance spectroscopy of laboratory surfaces and the photometry of solar system objects.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 86; Apr. 10
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  • 72
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    Spectra of the Jovian ring and Amalthea (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Measurements made between 0.887 and 2.4 microns demonstrate that the Jovian ring and Amalthea have similar reflection spectra. The spectra, in particular the ratio of the 0.9- to 2.2-micron reflectivities, are inconsistent with those expected from water, ammonia, or methane frosts, but are consistent with reflection from large rock bodies.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal; 86; Apr. 198
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  • 73
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    A companion quasar to 3C345 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The discovery of a new quasistellar object (QSO) which presents the strongest evidence to date for the membership of quasars in rich clusters is reported. During X-ray observations of quasar 3C345, a serendipitous X-ray source located 8 arcmin northeast of the quasar was discovered. The observed flux of the new source is 3.2 x 10 to the -13th erg/sq cm/sec in the 0.5-4.5 keV band. Three separate observations over a six-month period failed to show intensity variability in excess of the statistical uncertainty in the count rate. The spectrum shows a modest signal-to-noise ratio but four strong emission lines. It is suggested that the redshift agreement between the two QSOs indicates a common membership in a cluster of galaxies which may well be a rich cluster.
    Keywords: ASTROPHYSICS
    Type: Nature; 290; Apr. 9
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  • 74
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    Infrared observations of AE Aquarii (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Broadband infrared observations of the cataclysmic variable AE Aquarii are reported. The observations were obtained in the J, H, K and L filters with the InSb photometer attached to the 1-m telescope of the European Southern Observatory. The infrared energy distribution observed from 0.35 to 3.5 microns for phase 0.5 suggests a spectral type of K5 V for the secondary and a distance to the system of approximately 70 pc if an absolute magnitude of 7.3 is assumed. Monitoring of the flux at 2.2 microns reveals a variability with an amplitude of approximately 0.3 magnitude over one third of the orbital period, the nature of which is under investigation.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 93
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  • 75
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    An X-ray survey of nine historical novae (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Einstein Observatory Imaging Proportional Counter has been used to search for X-ray emission from nine nearby historical novae. Six of the novae have been detected with estimated X-ray intensities between 0.1 and 4 keV of 10 to the -13th to 10 to the -11th erg/sq cm-sec, comparable to the intensities of previously detected cataclysmic variables. The X-ray intensity of one of the novae, V603 Aql, varies over times of several hundred seconds. The data suggest a correlation between the decay rate of the historical outburst and the current X-ray luminosity. Alternatively, the X-ray luminosity may be related to the inclination of the binary system.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 244
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  • 76
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    A variable mixing-length ratio for convection theory (1981)
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    Publication Date: 2011-08-18
    Description: It is argued that a natural choice for the local mixing length in the mixing-length theory of convection has a value proportional to the local density scale height of the convective bubbles. The resultant variable mixing-length ratio (the ratio between the mixing length and the pressure scale height) of this theory is enhanced in the superadiabatic region and approaches a constant in deeper layers. Numerical tests comparing the new mixing length successfully eliminate most of the density inversion that typically plagues conventional results. The new approach also seems to indicate the existence of granular motion at the top of the convection zone.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 244
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  • 77
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    Voyager measurement of the rotation period of Saturn's magnetic field (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Saturn's radio rotation period is determined using measurements made by the Planetary Radio Astronomy experiment onboard the Voyager spacecraft. The sidereal period deduced is 10 hr 39 min 24 sec + or 7 sec. The radio rotation period is presumably that of the planet's magnetic field. A provisional Saturn longitude convention is proposed, and equations are provided to compute a longitude emphemeris and to transform between the proposed system and the (10 hr 14 min) system used for the Pioneer 11/Saturn encounter. In addition, the degree of longitude smearing which could result over the long term from the merging of data sets organized in this system is evaluated. Finally, no evidence of control of the radio emission by any of Saturn's satellites is found.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 8; Mar. 198
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  • 78
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    Radio science investigations of the Saturn system with Voyager 1 - Preliminary results (1981)
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    Publication Date: 2011-08-18
    Description: Analyses of Voyager 1 radio occultation measurements of the Saturn atmosphere near 75 deg south latitude and of the Titan equatorial atmosphere are presented. Molecular nitrogen appears to be the primary atmospheric constituent of Titan, whose clouds are probably methane ice. Solar abundance considerations of the data suggest large quantities of surface methane near its triple-point temperature, so that the three phases of methane could play a role on Titan analogous to that of water on earth. Ionospheric electron concentration and plasma scale height for the Saturn polar cap and monochromatic attenuation of the Saturn rings are also considered, along with radio tracking figures for the masses of two moons, Rhea and Titan.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 212; Apr. 10
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  • 79
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    Pulsar and diffuse contributions to observed galactic gamma radiation (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The first calculation of a gamma-ray production spectrum from pulsars in the Galaxy, along with a statistical analysis of data on 328 known radio pulsars, are presented. The implications of this point source contribution to the general interpretation of the observed galactic gamma-ray spectrum are indicated. The contributions from diffuse interstellar cosmic-ray induced production mechanisms are then re-examined, concluding that pulsars may be contributing significantly to the galactic gamma-ray emission.
    Keywords: ASTRONOMY
    Type: Nature; 290; Mar. 26
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  • 80
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    Dipole and quadrupole anisotropy of the 2.7 K radiation (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results of measurements of the dipole and quadrupole anisotropy of the microwave background radiation are reported. Balloon-borne measurements of the temperature difference between two horn antennas pointed 90 deg apart and 45 deg from the zenith were carried out at frequencies of 24.8, 31.4 and 46.0 GHz to determine three dipole and four quadrupole parameters. When combined with data from two previous balloon flights, a dipole anisotropy of 3.78 + or - 0.30 mK in the direction 11.6 + or - 0.2 h RA, -12 + or - 5 deg dec is obtained. The measurements reveal a spectral index of 0.04 + or - 0.28 between 19.0 and 46.0 GHz, indicating that the dipole effect arises from an intrinsic anisotropy in the temperature of the background and/or a first-order Doppler shift due to solar motions. A statistically significant quadrupole effect is also detected which is attributed to the intrinsic anisotropy of the 2.7 K background.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 81
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    Far-ultraviolet spectra and flux distributions of some Orion stars (1981)
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    Publication Date: 2011-08-18
    Description: Far-ultraviolet (950-1800 A) spectra with about 2 A resolution were obtained of a number of stars in Orion during a sounding-rocket flight 1975 December 6. These spectra have been reduced to absolute flux distributions with the aid of preflight calibrations. The derived fluxes are in good agreement with model-atmosphere predictions and previous observations down to about 1200 A. In the 1200-1080 A range, the present results are in good agreement with model predictions but fall above the rocket measurements of Brune, Mount and Feldman. Below 1080 A, our measurements fall below the model predictions, reaching a deviation of a factor of 2 near 1010 A and a factor of 4 near 950 A. The present results are compared with those of Brune et al. via Copernicus U2 observations in this spectral range, and possible sources of discrepancies between the various observations and model-atmosphere predictions are discussed. Other aspects of the spectra, particularly with regard to spectral classification, are briefly discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 82
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    Infrared observations of the Saturnian system from Voyager 1 (1981)
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    Publication Date: 2011-08-18
    Description: Atmospheric chemistry analyses of Saturn based on Voyager 1 infrared spectral and radiometric data are presented, including characteristics of the planet's rings and of Titan and other satellites. Infrared spectra of Saturn indicate the presence of H2, CH4, NH3, PH3, C2H2, and C2H6, with the possibility of C3H4 and C3H8. The atmospheric thermal structure of the planet shows hemispheric asymmetries that are consistent with seasonally varying insolation response, with an extensive small-scale latitudinal structure. Atmospheric chemistries of Titan, and optical and thermal characteristics for the rings of Saturn, are also given.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 212; Apr. 10
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  • 83
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    The cosmic X-ray background (1981)
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    Publication Date: 2011-08-18
    Description: The cosmic X-ray experiment performed with the A2 instrument on HEAO-1 was especially developed to make systematics-free measurements of the extragalactic X-ray sky and has yielded the broadband spectral characteristics for two extreme aspects of this radiation. For the apparently isotropic radiation of cosmological origin that dominates the extragalactic X-ray flux, the spectrum over the energy band of maximum intensity is remarkably well described by a thermal model with a temperature of a half-billion degrees. At the other extreme, broadband observations of individual extragalactic X-ray sources with HEAO-1 are restricted to objects within the present epoch. These X-ray sources include a large sample of active galaxies studied in some detail over a broad bandwidth for the first time. Details of the cosmic X-ray background at these two extremes are reviewed, and some models describing X-ray emission mechanisms are discussed.
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  • 84
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    Algol - A further study of the optical polarization (1981)
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    Publication Date: 2011-08-18
    Description: Results of a study of the phase-locked optical polarization of the Algol triple star system are presented. Polarimetry was obtained in the B filter during 75 nights from 1979 to 1980, and results were folded on the AB orbital period for the equatorial Stokes parameters Q and U. As expected for a nearly edge-on system, the polarization variations are predominantly in one direction of the Stokes-vector plane, and are mainly second-harmonic in character. The variable polarization indicates an eigendirection for the AB system at an angle of 137 + or - 4 deg, and a projected major axis of the third star at 133 + or - 3 deg with respect to the AB system. Considerations of the lowest-order theories of polarizing mechanisms, including limb polarization and reflection, indicate that the AB and AB-C orbital planes are almost normal to each other, rather than coplanar. An angular splitting in the Q-U curve between the two quadrature phases 0.25 and 0.75 is also found which can be explained by centrifugal flattening of the secondary's Roche lobe, or reflection from an optically thick, flattened gas cloud near the L1 point.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 85
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    Interstellar C2 molecules toward Omicron Persei (1981)
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    Publication Date: 2011-08-18
    Description: Seven weak interstellar absorption lines of the (2-0) Phillips band of C2 near the wavelength 8760 are detected in the spectrum of Omicron Persei. All of the lines have equivalent widths less than 2 mA and originate from the five lowest rotational levels of C2. The resulting total column density is N(C2) = 1.5 x 10 to the 13th/sq cm, and the excitation temperature is T = 116 plus or minus 16 K.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 86
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    Infrared and optical observations of the hydrogen lines in quasars (1981)
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    Publication Date: 2011-08-18
    Description: Infrared and optical spectrophotometric observations of the hydrogen lines in a sample of 16 quasars are discussed. The addition of these observations to previously published observations of hydrogen lines in quasars brings to 12 the number of quasars for which the P-alpha/H-alpha/H-beta line ratios have been measured and to nine the number of quasars for which the L-alpha/H-alpha line ratio has been measured. It is noted that the P-alpha/H-alpha ratios in low-redshift quasars are distributed around the case B value with a tendency toward values lower than that predicted by case B. The H-alpha/H-beta values in these same quasars are for the most part greater than the case B value. The tendency in the P-alpha/H-alpha/H-beta ratios is for the P-alpha/H-alpha ratio to decrease as the H-alpha/H-beta ratio increases. The decrease of the P-alpha/H-alpha ratio with increasing H-alpha/H-beta ratio is the most significant correlation obtained from the present data that any valid model of the line-emitting regions must explain. The low values of the L-alpha/H-alpha in comparison with the case B value are confirmed for a large sample of high-redshift quasars. L-alpha is seemingly destroyed rather than H-alpha being enhanced. It is concluded that reddening external to the emission-line regions cannot satisfactorily explain all the observed hydrogen line ratios.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 87
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    Nonthermal hard X-ray emission from the nucleus of NGC 1275 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations confirming the HEAO 1 discovery of a hard X-ray component in the X-ray spectrum of the Perseus cluster are reported. A comparison of the results with 1978 HEAO 1 observations and 1974 balloon limits shows that this component is variable on a time scale of one year. Synchrotron self-Compton models of the compact radio source centered on the nucleus of NGC 1275 predict a substantial secondary X-ray flux based on the observed radio data. While the observed X-ray flux is one-fourth the predicted value, uncertainties in the radio data are sufficient to account for the discrepancy. It is concluded that the hard X-ray flux originates in the active nucleus of the Seyfert galaxy NGC 1275 through the synchrotron self-Compton process.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 88
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    Very dusty galaxies (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The existence of a significant population of dust shrouded galaxies that do not emit much optical light but instead are primarily infrared sources is considered. It is noted that if very dusty galaxies are assumed to have a luminosity function similar to that of normal galaxies, then current observations seem to show that there are not more dusty galaxies than normal objects. Until more extensive infrared observations are obtained, however, it seems at least possible, though perhaps unlikely, that there are in fact a significant number of dusty galaxies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 243
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  • 89
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    Variable X-ray spectra of BL Lacertae objects - HEAO 1 observations of PKS 0548 - 322 and 2A 1219 + 305 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 243
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  • 90
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    Phase-correlated P Cygni profile variations of the C III multiplet in UW Canis Majoris (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The interacting close binary system UW CMa has been observed, in the wavelength range from 1161 to 1188 A, continuously during a complete orbital cycle in 1979 with the Copernicus (OAO-3) U2 spectrometer. The C III multiplet at 1175 A, observed as a P Cygni feature, exhbits a clear dependence on the orbital phase of the binary; the radial velocity variation of this feature lags behind that of the O7 primary component by 0.1 orbital phase, which agrees with the anticipations in an earlier study by the same authors. The radiation-driven matter, flowing out of the binary, originates in the primary component.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 94; 2, Fe; Feb. 198
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  • 91
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    A study of the Mg II k line in Beta Persei (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Spectral scans of the Mg II k line in Beta Per were obtained with Copernicus during two primary eclipses. A brief description of observation in a short frame mode is given. The observed data are compared with computed line profiles based on the eclipse geometry of spherical stars. It is shown that a nonuniform circumstellar envelope, or cloud, probably is present. In one scan, a red-shifted line of P Cygni-type profile appeared, indicating the occurrence of an unusual event in the close binary system.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 86; Feb. 198
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  • 92
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    VRI photometry of selected SAO stars (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Johnson V, R, and I photoelectric photometry has been obtained for 199 SAO stars in support of the Near Infrared Photographic Sky Survey. These data are utilized in the calibration of survey photographs and are presented here to assist other programs reliant upon access to photometry in the photographic infrared.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 92
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  • 93
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    The close multiple system mu Orionis - Masses and the mass-luminosity relation (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The observations made of the secondary component B of the close visual binary mu Ori are described. The Reticon observations made at red wavelengths showed the secondary to be a double-lined spectroscopic binary with a period of 4.78 days and nearly identical components having minimum masses of 1.1 solar mass each. Previous estimates are corroborated by the large spectroscopic mass ratio of B to A and B. The discovery that B is a pair of late-F dwarfs solves the apparent mass-luminosity relation discrepancy noted in previous studies.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 92
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  • 94
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    Comparative aspects of Venus and terrestrial meteorology (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The observations and measurements made by Pioneer Venus orbiters are presented in terms of comparison of Venus and terrestrial meteorology. Although the temperature-pressure profiles of the two planets differ at lower altitudes, the temperatures are similar over their common range of pressures except for a much cooler mesosphere on Venus. The additional similarities between the earth and Venus relate to the warm polar stratospheres and the zonally-averaged energy budgets of the two planets. A difference in the mean radiation budgets for Venus is the relative smallness of the upward and downward thermal flux components. It is noted that the observed similarities reflect common mechanisms despite the difference in the dynamical regimes of the two planets.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Weather; 36; Feb. 198
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  • 95
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    Earthlike planets: Surfaces of Mercury, Venus, earth, moon, Mars (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The surfaces of the earth and the other terrestrial planets of the inner solar system are reviewed in light of the results of recent planetary explorations. Past and current views of the origin of the earth, moon, Mercury, Venus and Mars are discussed, and the surface features characteristic of the moon, Mercury, Mars and Venus are outlined. Mechanisms for the modification of planetary surfaces by external factors and from within the planet are examined, including surface cycles, meteoritic impact, gravity, wind, plate tectonics, volcanism and crustal deformation. The origin and evolution of the moon are discussed on the basis of the Apollo results, and current knowledge of Mercury and Mars is examined in detail. Finally, the middle periods in the history of the terrestrial planets are compared, and future prospects for the exploration of the inner planets as well as other rocky bodies in the solar system are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 96
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    Deformation of a line-element in the phase space at the triangular libration point (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The flow in the projection of the phase space into the configuration space is presented in the neighborhood of a neutrally (or critically) stable equilibrium point in the restricted problem of three bodies. The projection is a line-element every point of which has zero initial velocity. After the elapse of various times the mapping (the rotations and elongations) of the line-element is described showing chaotic behavior.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 23; Feb. 198
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  • 97
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    Jupiter's magnetopause, bow shock, and 10-hour modulated magnetosheath Voyagers 1 and 2 (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This summary report discusses Jupiter's magnetopause, bow shock and magnetosheath, based on fine scale magnetic field data from the Voyager 1 and 2 encounters. Explicit models of the dawnside magnetopause and bow shock in Jupiter's orbital plane employ an axisymmetric parabola and hyperbola, respectively, and satisfy average boundary crossing positions, inbound and outbound; these models are determined separately for the two encounters. A new phenomenon has been discovered in Jupiter's magnetosheath. It is manifested as (5 or) 10 hour quasi-periodic modulation of the direction of the magnetic field in the outbound magnetosheath, predominantly in the northward (N) and southward (S) directions. It was seen to occur during both encounters and appears most evident in Voyager 2 outbound observations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters; 8; Jan. 198
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  • 98
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    Stability of outer planetary systems (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The conditions for stability in the Liapunov-Hill sense of outer planetary systems are given in terms of radii of planetary orbits. The outer planets of the solar system are found stable and the possible existence of other than the presently known planets between Jupiter and Pluto are indicated. The existence of other planetary systems with arbitrary mass ratios of the primaries is suggested, and the stability conditions for such systems are derived.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 23; Jan. 198
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  • 99
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    A model of temporal variations in ozone density in the Martian atmosphere (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Temporal variations of the ozone density profile in the Martian atmosphere at high latitudes are calculated for the course of a Martian year, taking into account seasonal and diurnal variations in temperature, water vapor and solar radiation. Calculations are based on a model including 35 neutral photochemical reactions, and vertical eddy diffusion using a time step of 12 min for the region from the surface to 240 km altitude. Results are found to be in better agreement with Mariner 9 observations of the time and magnitude of the seasonal maximum than previous model calculations. The diurnal variation is predicted to be small near the solstices, with the nighttime ozone density greater than the daytime and the magnitude of the difference dependent on season. Opposite temporal variations are predicted for ozone densities above and below about 25 km, and an ozone density maximum at 35-40 km is obtained. It is suggested that the effects of an aerosol layer may not be important in enhancing predicted ozone concentration, and may even decrease it.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Planetary and Space Science; 29; Jan. 198
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  • 100
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    In quest of telescopes (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This article deals with the author's decision to study star formation and reviews the early days of infrared astronomy at O'Brien Observatory. The infrared equipment used to observe the T Tauri variable class is described.
    Keywords: ASTRONOMY
    Type: Sky and Telescope; 61; Feb. 198
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