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  • Other Sources  (7,911)
  • ASTROPHYSICS  (4,662)
  • LUNAR AND PLANETARY EXPLORATION  (3,082)
  • Animals
  • Life and Medical Sciences
  • Niederschlag
  • Organic Chemistry
  • Review article
  • 1985-1989  (7,874)
  • 1945-1949  (18)
  • 1930-1934  (19)
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Keywords
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Year
  • 1
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    Erdbeben und das Problem ihrer Vorhersagbarkeit (1989)
    In:  Nova Acta Leopoldina, San Francisco, Pergamon, vol. NF 62, no. 270, pp. 83-97, pp. 1246
    Details
    Publication Date: 1989
    Keywords: Review article ; Earthquake precursor: prediction research
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Forces driving plate tectonics: The use of simple dynamical models (1989)
    In:  Reviews in Aquatic Sciences, Münster, Inst. f. Geophys., Ruhr-Univ. Bochum, vol. 1, no. 3-4, pp. 319-336, pp. B04310, (ISBN: 0534351875, 2nd edition)
    Details
    Publication Date: 1989
    Keywords: Stress ; Plate tectonics ; Modelling ; Review article
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
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    Evolution of the European continental crust: Deep drilling, Geophysics, Geology and Geochemistry (1989)
    In:  Tectonophysics special issue, Hannover, Conseil de l'Europe, vol. 157, no. 1-3, pp. 357-364, pp. L19605, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: CRUST ; Deep seismic sounding (espec. cont. crust) ; Review article ; Borehole geophys. ; Proceedings of a conference
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    BIBLIOGRAPHY SEISMOLOGY
  • 4
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    The crustal structure of western Europe (1989)
    In:  Ann. Rev. Earth Planet. Sci., Dordrecht, Netherlands, Dr. W. Junk, vol. 17, no. 2, pp. 335-360, pp. L08304, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Review article ; Deep seismic sounding (espec. cont. crust) ; Refraction seismics ; Muller ; ANREV
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    BIBLIOGRAPHY SEISMOLOGY
  • 5
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    IReservoir induced seismicity data management center developments at the University of Texas at Austin (1989)
    In:  Eos, Trans., Am. Geophys. Un., San Francisco, Pergamon, vol. 70, no. 20, pp. 602, pp. B05315, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Seismology ; Review article ; Seismic networks ; Data analysis / ~ processing
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    BIBLIOGRAPHY SEISMOLOGY
  • 6
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    A student's guide to and review of moment tensors (1989)
    In:  Seism. Res. Lett., Reykjavík, Icelandic Meteorological Office, Ministry for the Environment University of Iceland, vol. 60, no. 44 , pp. 37-57, pp. TC1011, (ISSN 0016-8548, ISBN 3-510-50045-8)
    Details
    Publication Date: 1989
    Keywords: Moment tensor ; Review article ; Fault plane solution, focal mechanism ; CLVD ; Seismology ; SRL ; FROTH ; MSOBIESIAK
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    BIBLIOGRAPHY SEISMOLOGY
  • 7
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    Introduction to the special issue on inverse problems (1989)
    In:  Wave Motion, Basel, Elsevier Science Publishers, vol. 11, no. 15, pp. 99-112, pp. L15S20, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Inversion ; Scattering ; holography ; Review article
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    BIBLIOGRAPHY SEISMOLOGY
  • 8
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    Die geophysikalische Erkundung Haithabus (1989)
    In:  Die Geowissenschaften, Leipzig, 3-4, vol. 7, no. 5769, pp. 225-229, pp. L06305, (ISBN: 0-12-018847-3)
    Details
    Publication Date: 1989
    Keywords: Seismics (controlled source seismology) ; archaeology ; radar ; Sea seismics ; Review article ; shallow ; Stuempel ; Stumpel
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    BIBLIOGRAPHY SEISMOLOGY
  • 9
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    Super-deep drilling and deep geophysical research seminar, U.S.S.R. (1989)
    In:  Eos, Trans., Am. Geophys. Un., Hokkaido University, Inst. f. Geophys., Ruhr-Univ. Bochum, vol. 70, no. 9, pp. 135, pp. 8038, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Review article ; KTB ; Borehole geophys. ; Applied geophysics
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    BIBLIOGRAPHY SEISMOLOGY
  • 10
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    Volcanic hazards and their mitigation: Progress and problems (1989)
    In:  Rev. Geophys., Warszawa, AGU, vol. 27(2), no. 1-2, pp. 237-269, pp. 2091, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Volcanology ; Review article ; Earthquake hazard ; Earthquake precursor: prediction research
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  • 11
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    Die kontinentale Unterkruste - ein Schwerpunktprogramm (1989)
    In:  Geowissenschaften, Taipei, AGU, vol. 165, no. 2, pp. 15-32, pp. B05403, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Review article ; CRUST ; Deep seismic sounding (espec. cont. crust) ; Geol. aspects
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  • 12
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    The Conrad discontinuity and the top of the reflective lower crust - do they coincide? (1989)
    In:  Tectonophys., Kunming, China, D. Reidel Publishing Company, vol. 157, no. 3-4, pp. 39-58, pp. L09303, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Review article ; CRUST ; Deep seismic sounding (espec. cont. crust) ; Geol. aspects ; Tectonics ; Plate tectonics
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  • 13
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    Seismic modelling of the earth's large-scale three-dimensional structure (1989)
    In:  Phil. Trans. R. Soc. London, Köln, Elsevier, vol. A 328, no. 4, pp. 291-308, pp. 1015, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Seismology ; Tomography ; Surface waves ; Shear waves ; Inversion ; Earth model, also for more shallow analyses ! ; earth mantle ; earth Core ; P-waves ; PKP ; PcP ; D" ; Review article ; Dziewonski
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  • 14
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    The core shadow zone boundary and lateral variations of the velocity structure of the lowermost mantle (1989)
    In:  Phys. Earth Planet. Int., Corvallis, x + 406 pp., Oregon State University Press, vol. 54, no. 1, pp. 64-81, pp. L13610, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Seismology ; earth mantle ; Review article ; Inhomogeneity ; Shear waves ; PEPI
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  • 15
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    Ergebnisse gesteinsphysikalischer Untersuchungen an Bohrkernen und ihre Bedeutung für das KTB (1989)
    Project Management of the Continental Deep Drilling Programme of the Fed. Rep. of Germany in the Geol. Survey of Lower Saxony
    In:  Bull., Polar Proj. OP-O3A4, Beiträge zum 2. KTB-Kolloquium, Hannover, Project Management of the Continental Deep Drilling Programme of the Fed. Rep. of Germany in the Geol. Survey of Lower Saxony, vol. 4, no. Subvol. a, pp. 130-140, (ISBN 0080419208)
    Details
    Publication Date: 1989
    Keywords: Borehole geophys. ; Laboratory measurements ; Physical properties of rocks ; Dearth Core ; Review article
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    BIBLIOGRAPHY SEISMOLOGY
  • 16
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    Quantification of Earthquakes and the Determination of Source Parameters (1989)
    In:  Tectonophys., London, 416 pp., Geological Society, vol. 166, no. 1, pp. 141-153, pp. L18607, (ISBN 1-86239-117-3)
    Details
    Publication Date: 1989
    Keywords: Source parameters ; Review article ; Seismology ; Source
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  • 17
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    Altersstruktur der Hochschullehrer im Fach Geophysik (1989)
    Dt. Geophys. Ges. e. V.
    In:  Mitteilungen, Hannover, Dt. Geophys. Ges. e. V., vol. 115, no. 1, pp. 7-8, pp. L05602, (ISBN: 0534351875, 2nd edition)
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    Publication Date: 1989
    Keywords: Review article
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  • 18
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    Gesteinsphysik im KTB-Feldlabor: Messungen und Ergebnisse (1989)
    Project Management of the Continental Deep Drilling Programme of the Fed. Rep. of Germany in the Geol. Survey of Lower Saxony
    In:  Bull., Polar Proj. OP-O3A4, Beiträge zum 2. KTB-Kolloquium, Hannover, Project Management of the Continental Deep Drilling Programme of the Fed. Rep. of Germany in the Geol. Survey of Lower Saxony, vol. 1, no. 4, pp. 120-129, (ISBN 0080419208)
    Details
    Publication Date: 1989
    Keywords: Borehole geophys. ; Laboratory measurements ; Physical properties of rocks ; Dearth Core ; Rock mechanics ; Physical properties of rocks ; Review article
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    BIBLIOGRAPHY SEISMOLOGY
  • 19
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    Mantle convection and plate tectonics: The emergence of paradigm in global geodynamics (1989)
    Gordon and Breach
    In:  Bull., Open-File Rept., Mantle Convection: Plate Tectonics and Global Dynamics, New York, Gordon and Breach, vol. 4, no. 1, pp. 1-22, (ISBN 0080419208)
    Details
    Publication Date: 1989
    Keywords: earth mantle ; Dynamic ; ConvolutionE ; Plate tectonics ; Review article
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    BIBLIOGRAPHY SEISMOLOGY
  • 20
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    Seismic monitoring of nuclear explosions (1989)
    Van Nostrand Reinhold
    In:  Bull., Open-File Rept., Encyclopedia of Geophysics, New York, Van Nostrand Reinhold, vol. 78, no. 87-17, pp. 1071-1089, (ISBN 0080419208)
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    Publication Date: 1989
    Keywords: Review article ; Nuclear explosion ; Seismology ; Detectors ; Discrimination
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    BIBLIOGRAPHY SEISMOLOGY
  • 21
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    Why squeeze rocks? (1989)
    In:  Eos, Trans., Am. Geophys. Un., Philadelphia, Wiley, vol. 70, no. 17, pp. 545, pp. 1497, (ISSN: 1340-4202)
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    Publication Date: 1989
    Keywords: Review article ; Rock mechanics ; Laboratory measurements
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  • 22
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    A report on the paper 'Characteristics of 96 underground nuclear explosions at the Semipalatinsk test sites', recently published in the Soviet Journal Atomnaya Energiya (1989)
    In:  Eos, Trans., Am. Geophys. Un., Veldhoven, Kluwer, vol. 70, no. 52, pp. 1569, pp. B05302, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Nuclear explosion ; Seismology ; Earthquake catalog ; Review article ; Source parameters
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    BIBLIOGRAPHY SEISMOLOGY
  • 23
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    Global patterns of tectonic stress (1989)
    In:  Nature, Stockholm, 3-4, vol. 341, no. B6, pp. 291-298, pp. L17317, (ISSN: 1340-4202)
    Details
    Publication Date: 1989
    Keywords: Stress ; Review article ; Stress measurements ; Mueller ; Muller ; Suarez ; Udias ; Bluemling ; Blumling
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    BIBLIOGRAPHY SEISMOLOGY
  • 24
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    The Earthquakes of Greece (1989)
    Ziti Publish. Co.
    In:  Thessaloniki, Ziti Publish. Co., vol. 15, no. Publ. No. 12, pp. 585, (ISBN 0080424309)
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    Publication Date: 1989
    Keywords: Review article ; Earthquake catalog ; Seismicity
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    BIBLIOGRAPHY SEISMOLOGY
  • 25
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    Aspects of acquisition and interpretation of deep seismic sounding data (1989)
    Plenum
    In:  Digital Seismology and Fine Modeling of the Lithosphere, New York, Plenum, vol. 37, pp. 121-132, (ISBN 0080419208)
    Details
    Publication Date: 1989
    Keywords: Deep seismic sounding (espec. cont. crust) ; Seismics (controlled source seismology) ; Data analysis / ~ processing ; Review article
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  • 26
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    The KTB pilot-hole: Tectonic setting, technical data and first results (1989)
    Springer
    In:  Professional Paper, The German Continental Deep Drilling Program (KTB), Site-Selection Studies in the Oberpfalz and Schwarzwald, Berlin, Springer, vol. 9, no. 16, pp. 527-553, (ISBN 1-4020-1729-4)
    Details
    Publication Date: 1989
    Keywords: Borehole geophys. ; KTB ; Tectonics ; Review article ; Geol. aspects
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  • 27
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    The role of continental scientific drilling in modern earth sciences, scientific rationale and plan for the 1990's (1989)
    Stanford University
    In:  report to the Interagency Coordinating Group for the Continental Scientific Program from the Workshop on Continental Drilling, Pittsburgh, Stanford University, vol. 10, no. 23, pp. 601-602, (ISBN 0 08 042822 3)
    Details
    Publication Date: 1989
    Keywords: Review article ; KTB ; Borehole geophys.
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  • 28
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    National Seismic System Science Plan (1989)
    U. S. Geological Survey
    In:  Circular No. 1031, 34 pp., New Orleans, Louisiana, U. S. Geological Survey, vol. C 560, 183 pp., no. PNL-CC-1801 171, pp. 977-992, (ISBN 3-933346-037)
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    Publication Date: 1989
    Keywords: Instruments ; Seismology ; Review article
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  • 29
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    Geophysical processes influencing the lower continental crust (1989)
    Am. Geophys. Union
    In:  Professional Paper, Open-File Rept., Properties and Processes of Earth's Lower Crust, Braunschweig, Am. Geophys. Union, vol. 16, no. 16, pp. 321-329, (ISBN 0080419208)
    Details
    Publication Date: 1989
    Keywords: Review article ; CRUST ; Dynamic ; Rock mechanics ; Muller
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  • 30
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    Earthquakes and crustal deformation (1989)
    Van Nostrand Reinhold
    In:  Bull., Open-File Rept., The Encyclopedia of Solid Earth Geophysics, New York, Van Nostrand Reinhold, vol. 13, no. 16, pp. 295-300, (ISBN 1-86239-165-3, vi + 330 pp.)
    Details
    Publication Date: 1989
    Keywords: Review article ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Earthquake ; Dislocation ; Geodesy ; Inelastic
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  • 31
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    Mechanical properties of lunar regolith and lunar soil simulant (1989)
    In:  CASI
    Details
    Publication Date: 2005-11-10
    Description: Through the Surveyor 3 and 7, and Apollo 11-17 missions a knowledge of the mechanical properties of Lunar regolith were gained. These properties, including material cohesion, friction, in-situ density, grain-size distribution and shape, and porosity, were determined by indirect means of trenching, penetration, and vane shear testing. Several of these properties were shown to be significantly different from those of terrestrial soils, such as an interlocking cohesion and tensile strength formed in the absence of moisture and particle cementation. To characterize the strength and deformation properties of Lunar regolith experiments have been conducted on a lunar soil simulant at various initial densities, fabric arrangements, and composition. These experiments included conventional triaxial compression and extension, direct tension, and combined tension-shear. Experiments have been conducted at low levels of effective confining stress. External conditions such as membrane induced confining stresses, end platten friction and material self weight have been shown to have a dramatic effect on the strength properties at low levels of confining stress. The solution has been to treat these external conditions and the specimen as a full-fledged boundary value problem rather than the idealized elemental cube of mechanics. Centrifuge modeling allows for the study of Lunar soil-structure interaction problems. In recent years centrifuge modeling has become an important tool for modeling processes that are dominated by gravity and for verifying analysis procedures and studying deformation and failure modes. Centrifuge modeling is well established for terrestrial enginering and applies equally as well to Lunar engineering. A brief review of the experiments is presented in graphic and outline form.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: First Annual Symposium. Volume 1: Plenary Session; 14 p
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  • 32
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    An upper limit on the high-energy gamma-ray emission of Vela X-1 (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The possibility of high-energy gamma-ray emission from the X-ray binary Vela X-1 was investigated by analyzing the COS-B satellite observations, using the COS-B X-ray detector for a phase coherent analysis in the search of rotational periodicity. The rotational upper limit is compared to the X-ray, TeV, and PeV fluxes reported by Chodil et al. (1967), North et al. (1984), and Protheroe et al. (1984), respectively. It was found that, under certain conditions, the upper limit determined here is not inconsistent with the reports of TeV and PeV emission.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 226; 1, De
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  • 33
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    Observations of non-thermal radiation from planets (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Nonthermal radio emissions from earth, Jupiter, Saturn, and Uranus are reviewed. The dominant source of emission at each planet appears to be AKR-like auroral emission in the X-mode. O-mode emissions are substantially responsible. There is a remarkably constant scaling factor relating the total solar wind input power into each planetary system and the AKR-like auroral emissions.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 34
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    Optical depth of molecular gas in starburst galaxies - Is M82 the prototype? (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An attempt is made to survey the CO(2-1) emission toward the centers of 17 IR-luminous galaxies which have previously been detected in CO(1-0). These galaxies span a wide range of size and L(FIR)/L(B) ratio, many have multiple-wavelength studies establishing them as starbursts, and some bear a morphological resemblance to M 82. Nine galaxies are detected and useful upper limits are placed on the remaining eight. Using the CO(2-1)/CO(1-0) ratio of antenna temperature as a diagnostic of optical depth, it is found that all of the galaxies contain predominantly optically thick molecular gas. This implies that the phase of starburst during which the molecular gas is optically thin, currently witnessed in M 82, is either uncommon or short-lived.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 225; 1, No
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    NASA TECHNICAL REPORTS
  • 35
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    The orbits of the satellites of Mars from spacecraft and earthbased observations (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This article presents the results of a fit of a model of the Martian satellite orbits to earthbased and spacecraft-based observations. An assessment of the orbit accuracies is given and the orbits are compared with those obtained by previous investigators.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 225; 2, No
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  • 36
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    Chronology and complexity of early lunar crust (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The petrology and chronology of early lunar crust is examined using the least equivocal of the available petrographic and age data on lunar rock samples, and the possible processes which produced the lunar crust are discussed. The results suggest that the lunar anorthositic crust was formed by about 120 Ma after the primary accretion of the moon at 4.56 Ga. At least some members of the diverse Mg-suites of rocks, such as norites, troctolites, and dunites, crystallized within a very few 100s of Ma after 4.56 Ga. A trace-element-rich material (KREEP) was formed by about 4.3 Ga ago, and this residue was subsequently reworked in melting and impact processes such that most samples which contain it have ages around 3.9-4.0 Ga. The findings also suggest that the onset of ferrous mare basalt volcanism began about 4.33 Ga, much earlier than was once assumed, and was still in process before the end of the most intense period of bombardment (3.9-4.0 Ga ago).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Tectonophysics (ISSN 0040-1951); 161; 157-164
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    NASA TECHNICAL REPORTS
  • 37
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    Phase transitions as the origin of large scale structure in the universe (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A review of the formation of large scale structure through gravitational growth of primordial perturbations is given. This is followed by a discussion of how symmetry breaking phase transitions in the early universe might have produced the required perturbations, in particular through the formation and evolution of a network of cosmic strings.
    Keywords: ASTROPHYSICS
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    NASA TECHNICAL REPORTS
  • 38
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    The Voyager 2 Neptune encounter (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The findings made by the Voyager 2 Neptune encounter are reviewed. Data on the bowshock, magnetic field, magnetosphere, rings, plasma sheet, aurora, moons, and dust of Neptune are discussed. Findings made concerning Triton are summarized.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: EOS (ISSN 0096-3941); 70; 915-921
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    NASA TECHNICAL REPORTS
  • 39
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    Mineralogical and chemical properties of the lunar regolith (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The composition of lunar regolith and its attendant properties are discussed. Tables are provided listing lunar minerals, the abundance of plagioclase feldspar, pyroxene, olivine, and ilmenite in lunar materials, typical compositions of common lunar minerals, and cumulative grain-size distribution for a large number of lunar soils. Also provided are charts on the chemistry of breccias, the chemistry of lunar glass, and the comparative chemistry of surface soils for the Apollo sites. Lunar agglutinates, constructional particles made of lithic, mineral, and glass fragments welded together by a glassy matrix containing extremely fine-grained metallic iron and formed by micrometeoric impacts at the lunar surface, are discussed. Crystalline, igneous rock fragments, breccias, and lunar glass are examined. Volatiles implanted in lunar materials and regolith maturity are also addressed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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    NASA TECHNICAL REPORTS
  • 40
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    Ring dynamics (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Theoretical models of planetary-ring dynamics are discussed in a detailed analytical review and illustrated with graphs and diagrams. The streamline concept is introduced, and the phenomena associated with the transport of angular momentum are described. Particular attention is then given to (1) broad rings like those of Saturn (shepherding, density-wave excitation, gaps, bending-wave excitation, multiringlet structures, inner-edge shepherding, and the possibility of polar rings around Neptune), (2) narrow rings like those of Uranus (shepherding, ring shapes, and a self-gravity model of rigid precession), and (3) ring arcs like those seen in stellar-occultation observations of Neptune.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Celestial Mechanics and Dynamical Astronomy (ISSN 0923-2958); 46; 3, 19
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    Report of the IAU/IAG/COSPAR working group on cartographic coordinates and rotational elements of the planets and satellites - 1988 (1989)
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    Publication Date: 2011-08-19
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Celestial Mechanics and Dynamical Astronomy (ISSN 0923-2958); 46; 2, 19
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  • 42
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    The search for evidence of particle acceleration at SN 1987A in MeV to PeV gamma rays (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The prospects for obtaining evidence of the particle acceleration by SN 1987A pulsar wind are discussed. It is noted that, of the seven experiments that searched for high-energy signals since the discovery of SN 1987A, operating in both the TeV region (air Cerenkov arrays) and the 100-TeV region (air shower arrays), not one has reported a continuous signal from the supernova. The only signal reported so far that could be interpreted as a signal from the supernova remnant is from an air shower experiment YANZOS (Bond, 1988), in which a transient flux of photons above 3 TeV was observed. It is pointed out however, that, if a TeV signal is seen, the accompanying gamma-ray flux around 100 MeV should be well above threshold for detection by the EGRET detector on Gamma-Ray Observatory.
    Keywords: ASTROPHYSICS
    Type: New York Academy of Sciences, Annals (ISSN 0077-8923); 571; 522-531
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  • 43
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    Neptune's wind speeds obtained by tracking clouds in Voyager images (1989)
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    Publication Date: 2011-08-19
    Description: Images of Neptune obtained by the narrow-angle camera of the Voyager 2 spacecraft reveal large-scale cloud features that persist for several months or longer. The features' periods of rotation about the planetary axis range from 15.8 to 18.4 hours. The atmosphere equatorward of -53 deg rotates with periods longer than the 16.05-hour period deduced from Voyager's planetary radio astronomy experiment (presumably the planet's internal rotation period). The wind speeds computed with respect to this radio period range from 20 meters per second eastward to 325 meters per second westward. Thus, the cloud-top wind speeds are roughly the same for all the planets ranging from Venus to Neptune, even though the solar energy inputs to the atmospheres vary by a factor of 1000.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 245; 1367-136
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  • 44
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    Turbulent atmospheric plumes above line sources with an application to volcanic fissure eruptions on the terrestrial planets (1989)
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    Publication Date: 2011-08-19
    Description: The theory of turbulent plumes maintained above steady line sources of buoyancy is worked out in detail within the limitations of Taylor's entrainment assumption. It is applied to the structure of a pure plume injected into a stably stratified atmosphere. Volcanic basalt eruptions that develop from long, narrow vents create line source plumes, which rise well above the magmatic fire fountains playing near the ground level. The eruption of Laki in 1783 may provide an example of this style of eruption. Flood basalts are more ancient examples. Evidence of enormous fissure eruptions that occurred in the past on Mars and Venus also exists. Owing to the different properties of the atmospheres on these two planets from those on the earth, heights of line source plumes are expected to vary in the ratios 1:6:0.6 (earth:Mars:Venus). It is very unlikely that the observed increase of sulfur dioxide above the Venusian cloud deck in 1978 could have been due to a line source volcanic eruption, even if it had been a flood basalt eruption.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 46; 2662-267
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  • 45
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    On the identification of formaldehyde in Halley's comet (1989)
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    Publication Date: 2011-08-19
    Description: The v1 and v5 infrared bands of formaldehyde in Halley's comet have been synthesized, using a line-by-line model for solar infrared fluorescence from low-temperature H2CO. Fully resolved spectra were convolved to spectral resolutions comparable with those used on the IKS spectrometer on the Vega 1 spacecraft. Excellent agreement is obtained between the observed and modeled spectra, permitting a definite identification of H2CO in Halley's comet. The retrieved production rate is 4.5 + or - 0.5 x 10 to the 28th molecules/s, and the rotational temperature is probably less than 150 K, with a best-fit value of about 50 K. Production rates (or upper limits) are also retrieved from ground-based spectra of Comets Halley and Wilson (1986), and it is shown that the production rate of H2CO exhibits significant temporal variability, relative to H2O, in Comet Halley.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 344; 940-948
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  • 46
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    The orbital inclination of Cygnus XR-1 measured polarimetrically (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The X-ray binary Cyg XR-1/HDE 226868 was observed polarimetrically over one orbit at three different optical wavelengths. The standard theory of Brown, et al. (1978) is used to derive an orbital inclination i = 62 deg (+5 deg, -37 deg), where the error is the 90-percent-confidence interval derived by the method of Simmons, et al. (1980). The value of the orbital inclination is significantly lower than values based on polarimetric observations. The difference is a result of the observational protocols used. A bias toward larger values of the inclination caused by the tidal distortion of the primary is still found in the present result. The inclination derived corresponds to a mass of the compact component of 6.3 solar masses, above the maximum mass of any degenerate configuration consistent with general relativity except a black hole.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 344; 830-834
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  • 47
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    The infrared emission bands. II - A spatial and spectral study of the Orion bar (1989)
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    Publication Date: 2011-08-19
    Description: The 3-13 micron emission of the Orion Bar is spectroscopically and spatially studied. There are three emission components, one from 'classical' dust that accounts for the bulk of the emission longward of 20 microns, a second one from large amorphous carbon grains or polycyclic aromatic hydrocarbon (PAH) clusters accounting for the broad features, and a third from PAH molecules that accounts for the sharp bands. The 3.3 and 11.3 micron features, which are due to C-H modes, are well correlated spatially, while the 7.7 micron band, due to C=C modes, has a different distribution than the 3.3 and 11.1 micron bands. It is concluded that the sharp emission bands arise in the photodissociation transition region between the H II region and the molecular cloud and are not present in the H II region. The broad continuum feature from 11-13 microns is strong in both regions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 344; 791-798
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  • 48
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    Stability of polar rings around Neptune (1989)
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    Publication Date: 2011-08-19
    Description: An analytical and numerical study of the stability of polar rings around Neptune is presented. The stability proofs are based on various methods used to study gas disks in galaxies. It is shown that stable polar rings can exist despite energy dissipation by collisions between particles. Also, four equilibrium orientations which pass nearly over the pole of Neptune are found, two of which are stable in the presence of dissipation.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 81; 132-144
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  • 49
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    Lunar observatories (1989)
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    Publication Date: 2011-08-19
    Description: Issues related to the establishment of lunar observatories are briefly addressed. The advantages of placing an observatory in a crater at one of the poles, where permanent darkness exists, are pointed out, and the methods required to emplace and operate such an observatory are considered. Planning for the installation of the first set of observatory instruments is discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Spaceflight (ISSN 0038-6340); 31; 308
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  • 50
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    4U1722 + 11 - The discovery of an X-ray selected BL Lac object (1989)
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    Publication Date: 2011-08-19
    Description: The Uhuru X-ray source 4U1722 + 11 was observed using the microchannel-plate detector (High Resolution Imager) on the Einstein Observatory, and its coordinates measured to a precision of about 5 arcsec. A 16th-magnitude stellar object within the error circle was observed spectroscopically at CTIO, and at the AAT, and found to have a featureless continuum. Subsequent radio observations at the VLA have established that the object is a radio source at the level of 60 mJy, and optical polarization measurements have determined that the source exhibits variable polarization at the level of 10 percent. On the basis of these observations, it is concluded that 4U1722 + 11 is a member of the class of objects known as X-ray selected blazars of BL Lac objects.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 240; 33-39
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  • 51
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    AGB evolution in the Large Magellanic Cloud (1989)
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    Publication Date: 2011-08-19
    Description: Observations and theoretical studies of the evolution of massive asymptotic giant branch (AGB) stars in the Magellanic Clouds are reviewed. Recent results support the hypothesis that AGB is truncated, probably through mass loss, before these stars can attain the theoretically predicted maximum luminosity. In particular, IRAS observations of the LMC provide little evidence for the presence of highly obscured 'cocoon' stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science (ISSN 0004-640X); 156; 1-2,; 73-79
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  • 52
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    The signature of a black hole transit (1989)
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    Publication Date: 2011-08-19
    Description: This paper considers the possibility of identifying a black hole on the basis of the detection of some unique effect occurring during the transit of a black hole across the stellar disk of a companion star in a binary system. The results of Monte-Carlo calculations show that the amplitude of the photometric and polarimetric light curves in a typical X-ray binary is too small to be observed with present instrumentation, but that a black hole transit might be detectable in a binary having a large separation of the components. No binary system suggested as containing a stellar-mass-sized black hole is a like candidate to exhibit an observable transit signature, with the possible exception of X Persei/4U0352+30 described by White et al. (1976).
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science (ISSN 0004-640X); 155; 1, Ma
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  • 53
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    Far-infrared observations of thermal dust emission from supernova 1987A (1989)
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    Publication Date: 2011-08-19
    Description: Observations of SN1987A in the spectral range 18-35 microns taken on November 16 and 23, 1988, 632 and 639 days after core collapse, are reported. A strong and rather flat continuum underlies weak fine-structure lines from heavy elements and declines slowly between 24 and 30 microns. The spectral shape indicates thermal emission from an almost featureless dust component, probably graphite, with silicates contributing less than 20 percent of the emitting dust mass. Some of the emission may be an 'echo' of supernova light reflected from a preexisting dust cloud, but a better explanation which can account for the entirety of emission from infrared to gamma wavelengths, is that dust is being formed in the supernova ejecta. This also accounts more naturally for the inferred dust composition.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 340; 697-699
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  • 54
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    X-ray spectroscopy of the ultrasoft transient 4U 1543 - 47 (1989)
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    Publication Date: 2011-08-19
    Description: The X-ray transient 4U 1543 - 47 was observed in August 1983 by the Exosat observatory near the maximum of an outburst. The X-ray spectrum was measured using a gas scintillation proportional counter (GSPC) and a transmission grating spectrometer (TGS). A broad (FWHM about 2.7 keV) line at 5.9 keV is detected in the GSPC, which is interpreted as a redshifted and broadened iron K-alpha line. The line broadening and redshift may arise from either Compton scattering in a cool plasma with small optical depth and/or from Droppler and relativistic effects in the vicinity of compact object. The spectrum below 2 keV, obtained with the TGS, shows evidence for a broad emission feature at 0.74 keV, which may be an iron L-transition complex. However, such an emission feature could be an artifact caused by an anomalously low interstellar absorption by neutral oxygen. The contimuum emission is extremely soft and is well described by an unsaturated Comptonized spectrum from very cool plasma (kT = 0.84 keV) with large scattering depth.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 344; 320-324
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  • 55
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    Contributions of low-luminosity sources to the X-ray background (1989)
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    Publication Date: 2011-08-19
    Description: HEAO 1 A-2 data are used to determine hard X-ray fluxes, or upper limits, for complete optically selected samples of active and normal galaxies, in order to estimate or to constrain their local X-ray luminosity functions. It is found that the luminosity function of Seyfert nuclei must flatten down drastically shortly below the observational limit of Piccinotti et al (1982); little can be added by dwarf active nuclei hidden in otherwise normal galaxies. Also analyzed is the possible contribution to the X-ray background from galaxies with strong star-formation activity, in the light of the possibility of a substantial cosmological evolution suggested by recent radio and IRAS data.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 344; 125-134
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  • 56
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    Three-point correlations of galaxy clusters (1989)
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    Publication Date: 2011-08-19
    Description: A relation between two- and three-point correlation functions similar to that of galaxies is presently established by estimating the irreducible angular three-point correlation function of Abell clusters in distance classes 5 and 6, for Galactic latitudes below 40 deg. The shape of the three-point correlation function is fully consistent with the quadratic scaling law found by Groth and Peebles (1977) for galaxies. The three-point correlation function is inconsistent with the expectations from biasing.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 344; 75-88
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  • 57
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    An asymmetric outgassing model for cometary nongravitational accelerations (1989)
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    Publication Date: 2011-08-19
    Description: The standard nongravitation force model has been modified by allowing the water-vaproization curve to peak a certain number of days (DT) either before or after perihelion, and the modification is shown to often improve the data fit. The best fit to the astrometric data is generally achieved for a value of DT corresponding to the offset in the comet's visual light curve. The asymmetric model, which more accurately mimics the comet's outgassing history, suggests only weakly that the rotation direction of Comet Halley is direct, and it does not provide evidence that the rotation axis of Comet Kopff passed through its orbit plane in the early twentieth century. Approximate lag angles of 4 deg for Comet Halley and 10 deg for Comet d'Arrest are found using the asymmetric model, and it is noted that these values are lower than those obtained with the standard model.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 98; 1083-109
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  • 58
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    The IRAS Bright Galaxy Sample. IV - Complete IRAS observations (1989)
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    Publication Date: 2011-08-19
    Description: Total flux densities, peak flux densities, and spatial extents at 12, 25, 60, and 100 microns are presented for the 330 sources in the IRAS Bright Galaxy Sample. The flux density ratios S sub nu (60 microns)/S sub nu (100 microns) and S sub nu (12 microns)/S sub n (25 microns) are found to correlate with both the infrared luminosity and the ratio of IR to visible flux. The relation between these two flux density ratios is shown to follow that found previously, with different slopes appearing for the warmer and colder galaxies in the sample. The results suggest that single photon heating of small grains (often the dominant source of 12 and 25 micron radiation from galaxies) significantly affects the emission of some galaxies at 60 microns, and that optical depth effects may alter the emergent radiation at 12 and 25 microns.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 98; 766-797
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    Saturn - Jewel of the solar system (1989)
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    Publication Date: 2011-08-19
    Description: The phenomena of the Saturn system discovered by the Voyager missions are addressed. The characteristics of the rings, including grooves, spikes, and warps, are described, and the discovery of bombarded rings and young rings is discussed. The unique and unexplained properties of Enceladus are summarized, and the possibility that some moons of Saturn have been reassembled is addressed. The interaction of moons with the rings is examined, and the possibility that Titan's atmosphere may contain complex molecules that are the precursors of life is considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Planetary Report (ISSN 0736-3680); 9; 12-15
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  • 60
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    Global properties of infrared bright galaxies (1989)
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    Publication Date: 2011-08-19
    Description: Infrared flux densities of 182 galaxies, including 50 galaxies in the Virgo cluster, were analyzed using IRAS data for 12, 25, 60, and 100 microns, and the results were compared with data listed in the Point Source Catalog (PSC, 1985). In addition, IR luminosities, L(IRs), colors, and warm dust masses were derived for these galaxies and were compared with the interstellar gas masses and optical luminosities of the galaxies. It was found that, for galaxies whose optical diameter measures between 5 and 8 arcmin, the PSC flux densities are underestimated by a factor of 2 at 60 microns, and by a factor of 1.5 at 100 microns. It was also found that, for 49 galaxies, the mass of warm dust correlated well with the H2 mass, and that L(IR) correlated with L(H-alpha), demonstrating that the L(IR) measures the rate of star formation in these galaxies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 70; 699-722
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    The thermal structure of Triton's atmosphere - Pre-Voyager models (1989)
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    Publication Date: 2011-08-19
    Description: Spectral data from earth observations have indicated the presence of N2 and CH4 on Triton. This paper outlines the use of the 1-D radiative-convective model developed for Titan to calculate the current pressure of N2 and CH4 on Triton. The production of haze material is obtained by scaling down from the Titan value. Results and predictions for the Voyager Triton encounter are as follows: A N2-CH4 atmosphere on Triton is thermodynamically self consistent and would have a surface pressure of approximately 50 millibar; due to the chemically produced haze, Triton has a hot atmosphere with a temperature of approximately 130 K; Triton's troposphere is a region of saturation of the major constituent of the atmosphere, N2.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 973-976
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    A CO survey of regions around 34 open clusters (1989)
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    Publication Date: 2011-08-19
    Description: Results are presented from a systematic search for CO emission from regions around 34 young open clusters in the outer Galaxy. The clusters have well-determined distances ranging from about 1 to 5 kpc and ages not greater than about 100 Myr. It was found that some moderately young clusters have no associated CO emission. All the surveyed clusters younger than about 5 Myr have associated with them at least one molecular cloud more massive than 10,000 solar mass, while the molecular clouds associated with clusters older than about 10 Myr are not more massive than a few thousands solar masses. It was also found that molecular clouds are receding from young clusters at a rate of about 10 km/sec, and that they seem to be destroyed by their interaction with the stars. Sites of ongoing star formation were identified in a number of clouds associated with young clusters.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 70; 731-812
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  • 63
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    Shock-implanted noble gases. II - Additional experimental studies and recognition in naturally shocked terrestrial materials (1989)
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    Publication Date: 2011-08-19
    Description: The process by which ambient gases can be implanted into silicates by shocks was investigated by analyzing the noble-gas content of several experimentally and naturally shocked silicate samples. The retentivity of shock-implanted gas during stepwise heating in the laboratory was defined in terms of two parameters, namely, the activation energy for diffusion and the extraction temperature at which 50 percent of the gas is released, both of which correlate with the shock pressure. The experiments indicate that, with increasing shock pressure, gas implantation occurs through an increasing production of microcracks/defects in the silicate lattice. The degree of annealing of these defects control the degree of diffusive loss of implanted gas.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics (ISSN 0026-1114); 24; 113-123
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  • 64
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    External control of the Saturn kilometric radiation by the solar wind - Comparison between Voyager 1 and 2 observations (1989)
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    Publication Date: 2011-08-19
    Description: The long-term modulation of Saturn's nonthermal radio emission in the kilometric wavelength range has been studied based upon data obtained by Voyagers 1 and 2. A comparison of the ballistic and hydrodynamic propagation of solar wind features from the spacecraft to Saturn allows the uncertainty inherent in the projection to be determined. The results confirm the previous suggestion that momentum, ram pressure, and kinetic energy flux are the primary solar wind parameters that drive the nonthermal radio emission. It is suggested that, under certain conditions and for limited periods of time, the magnetic properties and time derivatives of the solar wind have increased importance.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Annales Geophysicae (ISSN 0980-8752); 7; 341-353
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  • 65
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    On the lower altitude limit of the Venusian ionopause (1989)
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    Publication Date: 2011-08-19
    Description: It has been observed from the plasma experiments on the Pioneer Venus Orbiter that the altitude of the upper boundary of the ionosphere decreases in response to increasing solar wind dynamic pressure. However, at pressures above about 2.5 x 10 to the -8th dynes/sq cm, the further decrease in the ionopause height is rather small. Following the model of Cloutier et al. (1969), it is suggested that during high solar wind conditions, when the ionopause is formed at lower altitudes, the solar wind induces vertical and horizontal flows which sweep away the ionospheric plasma that is produced locally by photoionization. As a result, a disturbed photodynamical ionosphere is formed which has the scale height of the ionizable neutral constituent. It is shown that such a photodynamical ionosphere is observed at the subsolar ionopause under these conditions. As a consequence of this interaction, the ionopause altitude is observed to follow the small-scale height of the ionizable species, atomic oxygen, showing only small changes with solar wind pressure.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 759-762
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    Theories of the origin and evolution of the giant planets (1989)
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    Publication Date: 2011-08-19
    Description: Following the accretion of solids and gases in the solar nebula, the giant planets contracted to their present sizes over the age of the solar system. It is presently hypothesized that this contraction was rapid, but not hydrodynamic; at a later stage, a nebular disk out of which the regular satellites formed may have been spun out of the outer envelope of the contracting giant planets due to a combination of total angular momentum conservation and the outward transfer of specific angular momentum in the envelope. If these hypotheses are true, the composition of the irregular satellites directly reflects the composition of planetesimals from which the giant planets formed, while the composition of the regular satellites is indicative of the composition of the less volatile components of the outer envelopes of the giant planets.
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    Coupled evolution of the atmospheres and interiors of planets and satellites (1989)
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    Publication Date: 2011-08-19
    Description: The evolution of a planetary atmosphere can be powerfully influenced by the planetary interior's function as both a source and a sink of atmospheric constituents; the interior can in turn be strongly influenced by the atmosphere because the mechanism of interior heat loss depends on a volatile content for which the atmosphere can serve both as sink and source. The dependence of mantle rheology on volatile content could furnish a feedback mechanism tending to keep regassing/degassing in balance, thereby maintaining a relatively constant atmospheric mass. Consideration of the abundances of radiogenic and nonradiogenic noble gases in the earth's atmosphere, and of the fluxes of these gases from the mantle, support a large degassing event early on, followed by a decrease in degassing efficiency with time and relatively inefficient outgassing over most of geologic time.
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    Asteroid volatiles inventory (1989)
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    Publication Date: 2011-08-19
    Description: Asteroids appear in light of telescopic and meteority studies to be the most accessible repositories of early solar system history available. In the cooler regions of the outer asteroid belt, apparently unaffected by severe heating, the C, P, and D populations appear to harbor significant inventories of volatiles; the larger primordial belt population may have had an even greater percentage of volatile-rich, low-albedo asteroids, constituting a potent asteroid for veneering early terrestrial planet atmospheres. The volatile-rich asteroids contain carbon, structurally bound and adsorbed water, as well as remnants of interstellar material predating the solar system.
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    Voyager's decade of wonder (1989)
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    Publication Date: 2011-08-19
    Description: The development and implementation of the Voyager missions are reviewed. The interplanetary missions preceding Voyager are discussed, focusing on the technological development leading up to the Voyager spacecraft. The main results from Voyager observations of Jupiter, Saturn, and Uranus are outlined. Also, consideration is given to the prospects for observations of Neptune.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Sky and Telescope (ISSN 0037-6604); 78; 16-20
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    On structural patterns in H II regions (1989)
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    Publication Date: 2011-08-19
    Description: High-resolution photographs of H II regions show that a large number of stars embedded in the nebulosities appear to be surrounded by 'emply' spaces. This phenomenon seems to be quite common but has escaped attention up to now. The effect is not a photographic one, nor does it arise in the half-tone reproduction processes employed in publications, but no satisfactory explanation is apparent.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 101; 547-554
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    The formation of weathering products on the LEW 85320 ordinary chondrite - Evidence from carbon and oxygen stable isotope compositions and implications for carbonates in SNC meteorites (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Isotopic analysis of nesquehonite recovered from the surface of the LEW 85320 H5 ordinary chondrite shows that the delta C-13 and delta O-18 values of the two generations of bicarbonate (Antarctic and Texas) are different: delta C-13 = + 7.9 per mil and + 4.2 per mil; delta O-18 = + 17.9 per mil and + 12.1 per mil, respectively. Carbon isotopic compositions are consistent with equilibrium formation from atmospheric carbon dioxide at - 2 + or - 4 C (Antarctic) and + 16 + or - 4 C (Texas). Oxygen isotopic data imply that the water required for nesquehonite precipitation was derived from atmospheric water vapor or glacial meltwater which had locally exchanged with silicates, either in the meteorite or in underlying bedrock. Although carbonates with similar delta C-13 values have been identified in the SNC meteorites EETA 79001 and Nakhla, petrographic and temperature constraints argue against their simply being terrestrial weathering products.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics (ISSN 0026-1114); 24; 1-7
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    Meteoritic silicon carbide and its stellar sources - Implications for galactic chemical evolution (1989)
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    Publication Date: 2011-08-19
    Description: Interstellar silicon carbide grains in meteorites provide a novel means for studying the carbon-star population of about 5 x 10 to the 9th years ago. Their C-12/C-13 ratios differ greatly from the solar value but resemble those of present-day csrbon stars, implying little change in the galactic C-13 inventory. Isotope data on nitrogen and silicon suggest that the silicon carbide grains come mainly from red giants, with small contributions from novae.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 339; 351-354
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    A CCD portrait of Comet P/Tempel 2 (1989)
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    Publication Date: 2011-08-19
    Description: The development of activity in Comet P/Tempel 2 is studied from aphelion (R = 4 AU) to perihelion (R = 1.4 AU) using extensive time-series CCD photometry and CCD spectra. The comet undergoes a profound morphological change at R of about 2-2.5 AU, from a bare nucleus at larger distances to an active comet supporting a coma of gas and dust. Cyclic photometric variations with the period T = 8.95 + or - 0.01 hr. are present at all R, and are attributed to the rotation of the nucleus at this period. The nucleus is prolate (axes a:b:c = 1.9:1:1), a property shared with other nuclei studied using CCD photometry. Novel results include a limit on the bulk density of the nucleus, rho above 300 kg/cu m, and a 20-A-resolution CCD spectrum of the nucleus. Spatially and temporally resolved photometry is used to study the effects of nucleus rotation on the coma. The coma does not share the dramatic photometric variations shown by the nucleus. It possesses a steep surface-brightness distribution, which is attributable to progressive destruction of the coma grains with increasing space exposure.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 97; 1766-179
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  • 74
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    IRAS observations of optically selected galaxies. I - The properties of the UGC redshift sample (1989)
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    Publication Date: 2011-08-19
    Description: The FIR properties of more than 2400 optically selected galaxies in the Uppsala General Catalog are examined. The galaxies were detected by IRAS at 60 and 100 microns and have measured redshifts. A simple radiative transfer model is presented to study the nature of dust-heating sources. It is shown that for many normal disk galaxies, dust heated by old disk stars competes with dust heated by UV photons from newly formed stars. It is found that the 60-micron/100-micron flux density ratio may be used as an indicator of the dominant dust-heating source. Scaling relations with galaxy size and mass are presented which make it possible to estimate the contributions of any cirrus-like component to the total FIR luminosity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 341; 129-150
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    Star formation rates and abundance gradients in disk galaxies (1989)
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    Publication Date: 2011-08-19
    Description: Analytic models for the evolution of disk galaxies are presented, placing special emphasis on the radial properties. These models are straightforward extensions of the original Schmidt (1959, 1963) models, with a dependence of star formation rate on gas density. The models provide successful descriptions of several measures of galactic disk evolution, including solar neighborhood chemical evolution, the presence and amplitude of metallicity and color gradients in disk galaxies, and the global rates of star formation in disk galaxies, and aid in the understanding of the apparent connection between young and old stellar populations in spiral galaxies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 339; 700-711
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    The Baade-Wesselink method applied to field RR Lyrae stars. III - YZ Capricorni, RV Phoenicis, and V440 Sagittarii (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Application of the Baade-Wesselink method to three field RR Lyrae variables reveals evidence of shock waves in the atmospheres of RV Phe and V440 Sgr (but not YZ Cap) during maximum light. The results yield distance moduli of 24.21 + or - 0.20 for M31, 18.26 + or - 0.20 for the LMC, and 18.85 + or - 0.20 for the SMC. Using the Sandage (1982) age/turn-off luminosity relationship of VandenBerg and Bell (1985), estimated ages of 18.8 Gyr for M92 and of 15.7 Gyr for 47 Tuc are derived.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 209; 1-2,; 154-164
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    The outer R Aquarii nebula - Comparison of 6 centimeter radio continuum and Balmer line emission (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The 6 cm radio continuum structure of the R Aquarii outer nebula is compared with CCD imagery of H-alpha and H-beta line emission. It is shown that the 6 cm VLA imagery is morphologically similar and quantitatively related spatially to Balmer line imagery. There is negligible interstellar or circumstellar absorption along the line of sight to the outer nebula. The 6 cm structure of the outer nebula is consistent with thermal bremsstrahlung emission by a hot, optically thin gas. Spectra of the outer R Aquarii nebula are suggestive of shock-wave heating. The approximate equality of mass loss and radiative cooling suggests that the system's wind is probably enough to power the outer nebula and may account for its long-term persistence.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 337; 795-802
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    Slow expansion of the shell of the recurrent nova T Pyxidis and detection of a faint extended envelope (1989)
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    Publication Date: 2011-08-19
    Description: New H-alpha narrow-based CCD imaging of the recurrent nova T Pyxidis and the detection of a very faint, extended H-alpha halo surrounding the already known shell are reported. A forbidden O III image containing an emitting shell with a morphology different from that of the H-alpha shell is presented, and measurements of the H-alpha shell expansion are reported which rule out the 1966 eruption date for the shell origin, assuming uniform expansion. It is proposed that the observed shell consists of slowly moving, solar abundance ejecta which are photoionized.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 337; 720-729
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    Radar observations of Comet Halley (1989)
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    Publication Date: 2011-08-19
    Description: Five nights of Arecibo radar observations of Comet Halley are reported which reveal a feature in the overall average spectrum which, though weak, seems consistent with being an echo from the comet. The large radar cross section and large bandwidth of the feature suggest that the echo is predominantly from large grains which have been ejected from the nucleus. Extrapolation of the dust particle size distribution to large grain sizes gives a sufficient number of grains to account for the echo. The lack of a detectable echo from the nucleus, combined with estimates of its size and rotation rate from spacecraft encounters and other data, indicate that the nucleus has a surface of relatively high porosity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 338; 1094-110
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  • 80
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    Pre-main-sequence disk accretion in Z Canis Majoris (1989)
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    Publication Date: 2011-08-19
    Description: It is suggested that the pre-main-sequence object Z CMa is a luminous accretion disk, similar in many respects to the FU Orionis variables. Z CMa shows the broad, doubled optical absorption lines expected from a rapidly rotating accretion disk. The first overtone CO absorption detected in Z CMa is blue-shifted, suggesting line formation in a disk wind. Accretion at rates about 0.001 solar mass/yr over 100 yr is required to explain the luminosity of Z CMa. The large amount of material accreted (0.1 solar mass/yr) indicates that Z CMa is in a very early stage of stellar evolution, possibly in an initial phase of massive disk accretion.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 338; 1001-101
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    The optical/infrared counterpart(s) of IRAS 18333-2357 (1989)
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    Publication Date: 2011-08-19
    Description: Observations of the potential optical counterparts of the unusual source IRAS 18333-2357 are reported. There are three distinct optical objects located within roughly 2 arcsec of the IR source: a red star, a very blue star, and an extended emission line nebulosity. IRAS 18333-2357 indeed appears to be physically associated with the Galactic globular cluster M22, and while it probably should be considered a PN, its very small nebular mass and extreme abundance anomalies are very unusual among known PNe. IRAS 18333-2357 does not appear to be at an early stage of PN evolution, but instead may be in a late stage. The lack of an associated radio or H-alpha source is the result of abundance anomalies in the source.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 338; 862-874
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    RX Puppis - Detection of asymmetrical radio structure (1989)
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    Publication Date: 2011-08-19
    Description: Subarcsecond observations of the RX Puppis symbiotic system with the VLA have resolved 2 cm continuum emission which deviates from a previously reported circularly symmetric radio distribution. The radio structure is comprised of at least three nearly colinear components. Under the assumption that the strongest feature is coincident with the hot star, the other two features lie 230 and 590 AU distant. These radio features are reminiscent of small-scale radio structure detected toward R Aquarii, another symbiotic star system, and probably represents material ejected from the RX Puppis system at an earlier epoch.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 337; 514-519
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    On the generation of flux tube waves in stellar convection zones. I - Longitudinal tube waves driven by external turbulence (1989)
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    Publication Date: 2011-08-19
    Description: The source functions and the energy fluxes for wave generation in magnetic flux tubes embedded in an otherwise magnetic field-free, turbulent, and compressible fluid are derived. The calculations presented here assume that the tube interior is not itself turbulent, e.g., that motions within the flux tube are due simply to external excitation. Specific results for the generation of longitudinal tube waves are presented.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 337; 470-484
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    Multinational Mars exploration (1989)
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    Publication Date: 2011-08-19
    Description: A primary concern in the formation of a multinational Mars-exploration program is that of technology transfer, which would be most acute in the U.S./U.S.S.R. case but would exist in lesser degree among other nations. Another concern is that of management-complexity, which could inflate total costs and substantially counteract the anticipated benefits of spreading program costs among a number of nations. It is presently suggested that these problems can be substantially reduced by having each nation become responsible for one (or more) complete flight system. Each nation's role in mission operations must be clear, and the cleanliness of interfaces among flight systems must carry over into mission operations.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Aerospace America (ISSN 0740-722X); 27; 18-21
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    Test particle simulation study of whistler wave packets observed near Comet Giacobini-Zinner (1989)
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    Publication Date: 2011-08-19
    Description: Nonlinear interactions of water group ions with large-amplitude whistler wave packets detected at the leading edge of steepened magnetosonic waves observed near Comet Giacobini-Zinner (GZ) are studied using test particle simulations of water-ion interactions with a model wave based on GZ data. Some of the water ions are found to be decelerated in the steepened portion of the magnetosonic wave to the resonance velocity with the whistler wave packets. Through resonance and related nonlinear interaction with the large-amplitude whistler waves, the water ions become trapped by the packet. An energy balance calculation demonstrates that the trapped ions lose their kinetic energy during the trapped motion in the packet. Thus, the nonlinear trapping motion in the wave structure leads to effective energy transfer from the water group ions to the whistler wave packets in the leading edge of the steepened MHD waves.
    Keywords: ASTROPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 25-28
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    A second supernova inside Puppis A? (1989)
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    Publication Date: 2011-08-19
    Description: Narrow-band images of an unusual swirl structure located near the center of the Puppis A supernova remnant are presented which reveal three overlapping filamentary systems of highly diverse composition. One is dominated by emission lines of nitrogen, one by oxygen, and one by sulfur. Spectra indicate that these small rings have high velocities and a corresponding kinematic age of less than 800 yr. Heavy-element abundances are extremely high and different in each system, some reminiscent of knots in Cas A, and others of circumstellar matter observed surrounding supernova 1987A. The youth and unusual chemistry lead to the suggestion that a second supernova has exploded within the shell of Puppis A, giving rise to the swirl structure.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 337; 48-50
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  • 87
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    Formation of large-scale structure from cosmic strings and massive neutrinos (1989)
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    Publication Date: 2011-08-19
    Description: Numerical simulations of large-scale structure formation from cosmic strings and massive neutrinos are described. The linear power spectrum in this model resembles the cold-dark-matter power spectrum. Galaxy formation begins early, and the final distribution consists of isolated density peaks embedded in a smooth background, leading to a natural bias in the distribution of luminous matter. The distribution of clustered matter has a filamentary appearance with large voids.
    Keywords: ASTROPHYSICS
    Type: Physical Review Letters (ISSN 0031-9007); 62; 379-382
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    Molecule formation in fast neutral winds from protostars (1989)
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    Publication Date: 2011-08-19
    Description: A time-dependent chemical model is used to analyze the processes generating and destroying molecules in very high velocity winds from low-mass protostars. CO and SiO are found to be generated in significant quantities despite the persistence of H in atomic form, consistently with recent protostellar wind detections of CO and H I at velocities in excess of 100 km/sec. A moderate mass-loss rate, in conjunction with a temperature distribution that decreases rather rapidly with distance from the protostar, are the conditions for substantial molecule formation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 336; L29-L31
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    The orbital inclination of A0620 - 00 measured polarimetrically (1989)
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    Publication Date: 2011-08-19
    Description: The mass of the degenerate primary in A0620 - 00 is inferred from its spectroscopic mass function to be not less than 3.2 solar masses, making it an excellent candidate for a black hole. The exact value of the mass depends on the orbital inclination. The inclination of a binary system can be determined from the shape of its Stokes parameter light curves if the linear polarization of the system varies as a function of orbital phase. A0620 - 00 over one 8-hour binary period was observed with the 4.5-m equivalent MMT. Its polarization in the visible is variable with orbital phase. The standard theory of Brown et al. (1978) was used to derive an orbital inclination of i = 57 deg (+20 deg, -50 deg), where the error is the 90-percent confidence interval. An inclination of i = 57 deg corresponds to a mass of the compact primary of 6.6 solar masses, but the large uncertainty in the measured value of the inclination allows the derived mass of A0620 - 00 to be as low as 3.8 solar masses. If this is taken to be the maximum mass of any degenerate configuration consistent with general relativity except a black hole, then the mass of A0620 - 00 is still not well enough determined to conclude that it must be a black hole.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 101; 1135-113
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    Does mass accretion lead to field decay in neutron stars? (1989)
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    Publication Date: 2011-08-19
    Description: Adopting the hypothesis of accretion-induced magnetic field decay in neutron stars, the consequent evolution of a neutron star's spin and magnetic field are calculated. The results are consistent with observations of binary and millisecond radio pulsars. Thermomagnetic effects could provide a possible physical mechanism for such accretion-induced field decay.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 342; 656-658
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    Interstellar polycyclic aromatic hydrocarbons - The infrared emission bands, the excitation/emission mechanism, and the astrophysical implications (1989)
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    Publication Date: 2011-08-19
    Description: A comprehensive study of the PAH hypothesis is presented, including the interstellar, IR spectral features which have been attributed to emission from highly vibrationally excited PAHs. Spectroscopic and IR emission features are discussed in detail. A method for calculating the IR fluorescence spectrum from a vibrationally excited molecule is described. Analysis of interstellar spectrum suggests that the PAHs which dominate the IR spectra contain between 20 and 40 C atoms. The results are compared with results from a thermal approximation. It is found that, for high levels of vibrational excitation and emission from low-frequency modes, the two methods produce similar results. Also, consideration is given to the relationship between PAH molecules and amorphous C particles, the most likely interstellar PAH molecular structures, the spectroscopic structure produced by PAHs and PAH-related materials in the UV portion of the interstellar extinction curve, and the influence of PAH charge on the UV, visible, and IR regions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 71; 733-775
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    New features in Saturn's atmosphere revealed by high-resolution thermal infrared images (1989)
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    Publication Date: 2011-08-19
    Description: Observations of the stratospheric IR emission structure on Saturn are presented. The high-spatial-resolution global images show a variety of new features, including a narrow equatorial belt of enhanced emission at 7.8 micron, a prominent symmetrical north polar hotspot at all three wavelengths, and a midlatitude structure which is asymmetrically brightened at the east limb. The results confirm the polar brightening and reversal in position predicted by recent models for seasonal thermal variations of Saturn's stratosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Nature (ISSN 0028-0836); 342; 777-780
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    The Voyager 2 encounter with the Neptunian system (1989)
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    Publication Date: 2011-08-19
    Description: An overview of the Voyager 2 encounter with Neptune is presented, including a brief discussion of the trajectory, the planned observations, and highlights of the results described in the 11 companion papers. Neptune's blue atmosphere has storm systems reminiscent of those in Jupiter's atmosphere. An optically thin methane ice cloud exists near the 1.5-bar pressure level, and an optically thick cloud exists below 3 bars. Neptune's magnetic field is highly tilted and offset from the planet's center; it rotates with a period of 16.11 hours. Two narrow and two broad rings circle the planet; the outermost of these rings has three optically thicker arc segments. Six new moons were discovered in circular prograde orbits, all well inside Triton's retrograde orbit. Triton has a highly reflective and geologically young surface, a thin nitrogen atmosphere, and at least two active geyser-like plumes.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 246; 1417-142
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    Processes affecting the composition and structure of silicate grains in cometary nuclei (1989)
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    Publication Date: 2011-08-19
    Description: Characteristics which might be observed in silicate grains from a cometary nucleus are examined on the basis of theoretical studies of the life cycle of refractory grains and laboratory experiments using simple analogs to the complex natural system. The life-cycle of a typical silicate grain is reviewed from condensation in a circumstellar outflow to incorporation into a cometary parent body. The possibility for grain metamorphism in the cometary environment is discussed and results are presented from experiments on the properties of interstellar grains. Also, consideration is given to the information about presolar refractory grains that might be gained from studying samples returned from a cometary nucleus.
    Keywords: ASTROPHYSICS
    Type: Earth, Moon, and Planets (ISSN 0167-9295); 47; 33-50
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    The Exosat spectral survey of AGN (1989)
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    Publication Date: 2011-08-19
    Description: Results are presented from Exosat observations of 48 hard X-ray selected Seyfert-type active galactic nuclei (AGN). These include all 30 of the emission line AGN in the Piccinotti (1981) sample. Combining Exosat LE and ME data has yielded X-ray spectra over the broad energy range 0.1-10 keV. Spectra in the about 2-10 keV range are found to be well described by a simple power law, with a narrow distribution of spectral indices across the sample about a mean energy index alpha = 0.70. Exosat has also revealed a substantial number of sources with complex soft X-ray spectra. Evidence that soft emission components occur in many Seyferts, together with detection of rapid variability in the soft component, provides a quantitative support for an accretion disk model for AGN. Approximately half of the present sample of AGN show low-energy absorption attributable to substantial cold matter within the host galaxy. A few cases show evidence for column variability and reduced low-energy opacity (by photo-ionization). These results and the observed rarity of intrinsic absorption in the higher luminosity sources suggest the absorbing matter lies close to the central continuum source.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 240; 833-880
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    Large-scale cosmic microwave background anisotropies in isocurvature baryon open universe models (1989)
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    Publication Date: 2011-08-19
    Description: The large-angular-scale cosmic microwave background anisotropy is calculated in a low-density baryon-dominated universe with isocurvature primordial inhomogeneities. In models in which the initial power spectra of perturbations are steeper than white noise, predictions for the quadrupole moment of the anisotropy are found to be in conflict with existing observational limits, if the universe remained fully ionized and Compton drag inhibited growth of inhomogeneities until z = about 100. In order to lower the amplitude of the anisotropy, it is necessary to substantially prolong the duration of the growth phase of density perturbations, while smearing out fine-scale anisotropies, thereby requiring reionization to occur at a redshift smaller than 100, but larger than the redshift of the last scattering surface (in a reionized model).
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 346; L1-L4
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    Why DA and DB white dwarfs do not show coronal activity and p-mode oscillations (1989)
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    Publication Date: 2011-08-19
    Description: The problems of nonradiative heating of outer atmospheric layers and p-mode oscillations in white dwarfs caused by acoustic waves generated in convective zones are discussed. These effects have been studied by calculating the cutoff periods for adiabatic and isothermal waves propagating in atmospheres of DA and DB stars with Teff greater than or equal 20,000 K and log g = 6-9. The obtained cutoff periods are approximately bounded by 0.01 and 40 sec for high- and low-gravity white dwarfs, respectively. Expected amplitudes of p-mode oscillations corresponding to trapped acoustic waves with small angular wave numbers are estimated, indicating that the amplitudes could be observed as Doppler shifts of spectral lines which might be detectable if adequate spectral resolution were available. The luminosity variations corresponding to these amplitudes are unlikely to be observable when all damping processes are accounted for. Results also indicate that the present theory of convection predicts some irregularities in the behavior of physical parameters.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 346; 435-443
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  • 98
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    A search for methylene in the Orion nebula (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A deep search for the J = 4-3 and 5-4 fine-structure components of the N(KK) = 4(04)-3(13) rotational transition of methylene toward the hot core of the Orion KL nebula is conducted. An approximate 4-sigma emission feature which is frequency-coincident with a hyperfine blend of the J = 4-3 component is detected, and weak features (about 2-3 sigma) frequency-coincident with the resolved F = 6-5 and 5-4 hyperfine components of the J = 5-4 component are observed. The relative intensities of these spectral features and their observational repeatability suggest that assignment to interstellar CH2 is likely correct, although the result must be confirmed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 346; 794-798
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  • 99
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    The interiors of Pluto and Charon - Structure, composition, and implications (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent models of the internal structure of Pluto and Charon, made possible by analysis of the Pluto/Charon mutual events are reviewed. At a mean density of just over 2 g/cu cm and a predicted rock mass fraction of roughly 0.7, the Pluto/Charon system is significantly rockier than the icy satellites of the giant planets, a contrast which may reflect its formation in a CO-rich outer solar nebula rather than a circumplanetary nebula. Pluto and Charon may in fact be so rocky that they lost volatiles early in their history (possibly during a Charon-forming impact event), although this is still an open issue.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 16; 1209-121
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  • 100
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    Interstellar matter in early-type galaxies - Optical observations (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Results of optical observations of 26 bright elliptical galaxies selected on the basis of IRAS data are discussed. Optical broadband imaging (using B and R filters) and narrow-band imaging (using H-alpha interference filters) have been performed to study dust patches and ionized gas. Long-split spectroscopy has also been made to determine gas kinematics and relative line ratios. The spectroscopic data confirm the presence and distribution of interstellar matter (dust lanes and ionized gas) seen in the direct imaging. Decoupled kinematics of interstellar gas and stars favors an external origin of the interstellar matter. However, for one isolated galaxy, an internal origin is not excluded. The rotation curves determined by optical emission lines are symmetric around the center in most galaxies observed. Galaxy masses and mass-to-light ratios are estimated using the rotation curves of the ionized gas.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 346; 653-674
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