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  • 1
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    Investigation of the enhanced spatial density of submicron lunar ejecta between L values 1.2 and 3.0 in the earth's magnetosphere: Theory (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Initial results from the measurement conducted by the dust particle experiment on the lunar orbiting satellite Lunar Explorer 35 (LE 35) were reported with the data interpreted as indicating that the moon is a significant source of micrometeroids. Primary sporadic and stream meteoroids impacting the surface of the moon at hypervelocity was proposed as the source of micron and submicron particles that leave the lunar craters with velocities sufficient to escape the moon's gravitational sphere of influence. No enhanced flux of lunar ejecta with masses greater than a nanogram was detected by LE 35 or the Lunar Orbiters. Hypervelocity meteoroid simulation experiments concentrating on ejecta production combined with extensive analyses of the orbital dynamics of micron and submicron lunar ejecta in selenocentric, cislunar, and geocentric space have shown that a pulse of these lunar ejecta, with a time correlation relative to the position of the moon relative to the earth, intercepts the earth's magnetopause surface (EMPs). As shown, a strong reason exists for expecting a significant enhancement of submicron dust particles in the region of the magnetosphere between L values of 1.2 and 3.0. This is the basis for the proposal of a series of experiments to investigate the enhancement or even trapping of submicron lunar ejecta in this region. The subsequent interaction of this mass with the upper-lower atmosphere of the earth and possible geophysical effects can then be studied.
    Keywords: ASTROPHYSICS
    Type: NASA, Lyndon B. Johnson Space Center, Experiments in Planetary and Related Sciences and the Space Station; 9 p
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  • 2
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    Mass loading of the Earth's magnetosphere by micron size lunar ejecta. 1: Ejecta production and orbital dynamics in cislunar space (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Particulate matter possessing lunar escape velocity sufficient to enhance the cislunar meteroid flux was investigated. While the interplanetary flux was extensively studied, lunar ejecta created by the impact of this material on the lunar surface is only now being studied. Two recently reported flux models are employed to calculate the total mass impacting the lunar surface due to sporadic meteor flux. There is ample evidence to support the contention that the sporadic interplanetary meteoroid flux enhances the meteroid flux of cislunar space through the creation of micron and submicron lunar ejecta with lunar escape velocity.
    Keywords: ASTROPHYSICS
    Type: NASA. Lyndon B. Johnson Space Center Space Station Planetology Experiments (SSPEX); 3 p
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  • 3
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    Mass loading of the Earth's magnetosphere by micron size lunar ejecta. 2: Ejecta dynamics and enhanced lifetimes in the Earth's magnetosphere (1986)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Extensive studies were conducted concerning the indivdual mass, temporal and positional distribution of micron and submicron lunar ejecta existing in the Earth-Moon gravitational sphere of influence. Initial results show a direct correlation between the position of the Moon, relative to the Earth, and the percentage of lunar ejecta leaving the Moon and intercepting the magnetosphere of the Earth at the magnetopause surface. It is seen that the Lorentz Force dominates all other forces, thus suggesting that submicron dust particles might possibly be magnetically trapped in the well known radiation zones.
    Keywords: ASTROPHYSICS
    Type: NASA. Lyndon B. Johnson Space Center Space Station Planetology Experiments (SSPEX); 3 p
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  • 4
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    NGC 1275 /3C 84/ - Similar structure in the optical and 3-mm radio variations (1979)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Optical and 3.3-mm data for the Seyfert galaxy NGC 1275 (3C 84) are compared. Similarities exist between the variations at the two wavelengths with regard to amplitude, time scale, and interval between events. The question is raised whether these similarities may be the result of a common triggering mechanism.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 91
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  • 5
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    Relativistic precessing jets in quasars and radio galaxies - Models to fit high resolution data (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The formulation of generalized models tracing the geometry and intensity of the synchrotron emission from precessing, twin, relativistic jets as projected on the plane of the sky is presented. It is shown that neither the shape of the image nor its relative intensities are altered by including the effects of a cosmological redshift and a relative velocity between the source and observer. The models are fitted to the available data for several quasars and radio galaxies and demonstrate the plausibility of the phenomenon. Probable selection effects are considered and diagnostics given for recognizing objects showing this behavior. In the radio galaxies considered, velocities up to about 0.2c and precession periods of 1,000,000 yr are deduced. In the QSOs investigated, velocities of 0.7c and greater are found and periods of order 10,000 yr. In some cases precession cone angles increase with time. Consequences in terms of lifetimes of QSO behavior and binary supermassive objects are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 262
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  • 6
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    High-resolution observations of gamma-ray line emission from SN 1987A (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Observations of SN 1987A made with a balloon-borne gamma-ray spectrometer comprising an array of high-purity germanium detectors on October 29-31, 1987 are presented. High resolution data, typically 2.5 keV at 1.33 MeV, were obtained for two transists of the supernova with interspersed background data. A preliminary estimation of line flux is presented. It is found that there is evidence of dynamical broadening of the 847 keV line. It is suggested that this line may be an emission from the first excited state of Fe-56 due to the radioactive decay of Co-56 providing evidence for nucleosynthesis in the supernova.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 334; L91-L94
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  • 7
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    Thermoluminescence and Antarctic meteorites (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The level of natural thermoluminescence (TL) in meteorites is the result of competition between build-up, due to exposure to cosmic radiation, and thermal decay. Antarctic meteorites tend to have lower natural TL than non-Antarctic meteorites because of their generally larger terrestrial ages. However, since a few observed falls have low TL due to a recent heating event, such as passage within approximately 0.7 astronomical units of the Sun, this could also be the case for some Antarctic meteorites. Dose rate variations due to shielding, heating during atmospheric passage, and anomalous fading also cause natural TL variations, but the effects are either relatively small, occur infrequently, or can be experimentally circumvented. The TL sensitivity of meteorites reflects the abundance and nature of the feldspar. Thus intense shock, which destroys feldspar, causes the TL sensitivity to decrease by 1 to 2 orders of magnitude, while metamorphism, which generates feldspar through the devitrification of glass, causes TL sensitivity to increase by a factor of approximately 10000. The TL-metamorphism relationship is particularly strong for the lowest levels of metamorphism. The order-disorder transformation in feldspar also affect the TL emission characteristics and thus TL provides a means of paleothermometry.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst. International Workshop on Antarctic Meteorites; p 83-100
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  • 8
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    Cathodoluminescence observations of in situ aqueous destruction of chondrules in the Murchison CM chondrite (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-01-25
    Description: A low-power cathodoluminescence (CL) mosaic of a 1x2 cm section of the Murchison CM chondrite contains chondrules of two types: one contains olivines with red CL and is thought to be the equivalent of group A chondrules of Sears et.; and one without observable CL, which is probably equivalent to their group B chondrules. Both types of chondrule contain dust mantles with a characteristic uniform red CL due to very fine-grained forsterites, but the mantles of group A chondrules have a complex internal structure and are much thicker than the relatively thin rims on the group B chondrules. The variety of internal textures and the progressive integration of the objects with the surrounding matrix suggests to us that these features are large group A chondrules in the process of being destroyed by aqueous alteration. Prior to aqueous alteration, group A chondrules in CM chondrites were larger than group B chondrules, which is contrary to the situation in ordinary chondrites and were apparently destroyed more rapidly than group B chondrules by aqueous alteration.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z; p 1269-1270
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  • 9
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    The group A3 chondrules of Krymka: Further evidence for major evaporative loss during the formation of chondrules (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Like Semarkona (type 3.0), Krymka (type 3.1) contains two distinct types of chondrule (namely groups A and B) which differ in their bulk compositions, phase compositions, and CL properties. The group A chondrules in both meteorites show evidence for major loss of material by evaporation(i.e. elemental abundance patterns, size, redox state, olivine-pyroxene abundances). Group A and B chondrules probably formed from common or very similar precursors by the same processes acting with different intensities, group A suffering greater mass-loss by evaporation and reduction of FeO and SiO2. While Krymka chondrules share many primary mineralogical and compositional properties with Semarkona chondrules, the minimal metamorphism it has suffered has also had a significant effect on its chondrules.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 2: G-M; p 681-682
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  • 10
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    Meteorites from recent amor-type orbits (1993)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: We report here the discovery of a recent meteorite shower in Antarctica, the members of which have very high natural thermoluminescence levels. It is apparent from these data that the shower has been on Earth only a short time (approximately 1000 years) and the meteorite probably came to Earth through rapid (less than 10 exp 5 years) evolution from an orbit with perihelion greater than 1.1 AU, similar to Amor asteroids. Only a very small number of meteorites, including a few modern falls, appear to have had similar orbital histories.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F; p 93-94
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