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  • Other Sources  (909)
  • AERODYNAMICS  (546)
  • ASTRONOMY  (363)
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  • 2015-2019
  • 1985-1989  (909)
  • 1950-1954
  • 1988  (909)
  • 1
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    V482 Cygni - An R Coronae Borealis star in a quadruple system (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations of the R CrB variable star V482 Cyg, obtained with the University of Rochester 32 x 32 InSb array camera at the NASA IR Telescope Facility on Mauna Kea on August 20, 1984, are reported. The data-reduction and analysis procedures are described in detail, and the results are presented in tables and maps. V482 Cyg is shown to be a member of a quadruple system or perhaps a small obscured cluster. Parameters determined include distance 1.7 kpc, circumstellar-shell temperature 800 K, and absolute magnitude M(V) = -2.8.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 100; 388-392
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  • 2
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    The 1985 May superoutburst of the dwarf nova OY Carinae. II - IUE and Exosat observations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ultraviolet (IUE) and X-ray (Exosat) observations of the eclipsing dwarf nova OY Carinae during the superoutburst of May 1985 are presented. From the lack of X-ray eclipse and UV behavior, it is deduced that the X-ray flux originates in an optically thin corona comparable in size to the Roche lobe, and not directly from the white dwarf or boundary layer. The asymmetric UV line emission originates partly in the accretion disk and partly in a wind. There is a strong modulation of the UV continuum flux that is thought to be caused by extended vertical disk structure shadowing the inner regions.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 231; 237-255
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  • 3
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    Trojan and Hilda asteroid lightcurves. I - Anomalously elongated shapes among Trojans (and Hildas?) (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A comparison of the available sample of lightcurves for 26 Trojan and Hilda asteroids with belt asteroid lightcurves shows the former to be distinguished by a higher incidence of high amplitudes rgan belt asteroids of comparable size, suggesting more elongated shapes; they currently have, moreover, only a few percent of the main-belt asteroids' collision frequency. A more modest collisional evolution that may have affected the relative degree of fragmentation of these bodies, and thus their shapes, is inferred.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 487-498
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  • 4
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    Force and pressure study of thick cambered/twisted 58 deg delta wings (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 69-75
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  • 5
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    Progress in analysis and prediction of dynamic stall (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 6-17
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  • 6
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    Astrometric results of 1978-1985 Deep Space Network radio interferometry - The JPL 1987-1 extragalactic source catalog (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An astrometric radio reference frame has been determined from intercontinental dual-frequency radio interferometric measurements. These measurements were carried out on a regular basis during 1978-1985 between NASA's Deep Space Network stations in California, Spain, and Australia. Analysis of 6800 pairs of delay and delay-rate observations made during 51 sessions produced estimates of 1300 parameters. The most significant of these are geophysical quantities and positions of extragalactic sources. The source catalog resulting from this analysis includes 106 sources fairly uniformly distributed over the celestial sphere, north of -45 deg declination. Almost all of the resulting source positions have formal uncertainties between 0.5 and 3 milliarcseconds (mas), with rms values of 2 mas in both angular coordinates. Internal consistency checks, as well as comparisons with independently determined source catalogs of comparable quality, indicate that relative source coordinates determined by VLBI contain systematic errors at the level of 1 to 2 mas.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 95; 1647-165
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  • 7
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    Two-component LDV investigation of three-dimensional shock/turbulent boundary-layer interactions (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 52-56
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  • 8
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    Asteroid 45 Eugenia - Lightcurves and the pole orientation (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Three lightcurves obtained in 1969 and six from 1984 are presented for the 250-km U-type asteroid Eugenia. The asteroid's north pole is within + or - 10 deg of ecliptic longitude 106 deg and a latitude of +26 deg, in keeping with an amplitude-aspect pole analysis. While only one maximum and one minimum are present when observations are closest to both the north and south poles, there are two of each at other oppositions. It is suggested that this effect may be due to the surface albedo features of Eugenia.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 73; 314-323
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  • 9
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    A CO survey of the southern Milky Way - The mean radial distribution of molecular clouds within the solar circle (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 324; 248-266
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  • 10
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    Statistical error analysis in CCD time-resolved photometry with applications to variable stars and quasars (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Differential photometric time series obtained from CCD frames are tested for intrinsic variability using a newly developed analysis of variance technique. In general, the objects used for differential photometry will not all be of equal magnitude, so the techniques derived here explicitly correct for differences in the measured variances due to photon statistics. Other random-noise terms are also considered. The technique tests for the presence of intrinsic variability without regard to its random or periodic nature. It is then applied to observations of the variable stars ZZ Ceti and US 943 and the active extragalactic objects OQ 530, US 211, US 844, LB 9743, and OJ 287.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 95; 247-256
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  • 11
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    IRAS observations of radio galaxies (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: IRAS measurements at 25, 60, and 100 microns have been used to analyze the far-infrared properties of radio galaxies. Fifty-eight of the 131 objects surveyed were detected at the level of better than 300 mJy at 60 microns. The most powerful radio galaxies are strong emitters in the far infrared. Large infrared emission is shown to be correlated with the presence of strong emission lines in the optical spectra. The infrared colors of the strong radio galaxies are similar to those of Markarian Seyferts. The results are shown to be consistent with recent results implying that the host galaxies of radio sources are not normal giant ellipticals and that galaxy-galaxy interactions may power luminous radio sources. Finally, some similarities between powerful radio galaxies and powerful infrared galaxies are noted and briefly discussed.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 95; 26-36
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  • 12
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    The project EGRET (Energetic Gamma-Ray Experiment Telescope) on NASA's Gamma-Ray Observatory (GRO) (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The design, predicted performance, and scientific objectives of the 20-30,000-MeV gamma-ray telescope EGRET for the NASA GRO spacecraft (scheduled for Space Shuttle launch to a 450-km 28.5-deg orbit in 1990) are reviewed. The other GRO instruments are briefly characterized, including the burst and transient-source experiment, the oriented scintillation spectrometer, and the imaging Compton telescope. EGRET comprises an anticoincidence system, a spark chamber, a triggering telescope, an NaI total-absorption spectrometer, a gas supply capable of refilling the chamber four times, and support electronics. EGRET will operate with energy resolution about 15 percent, effective area about 2000 sq cm, sensitivity about 5 x 10 to the -8th/sq cm sec, angular resolution 0.1-0.4 deg, and FOV about 40 deg FWHM. Observations of Galactic point sources, Galactic and extragalactic diffuse emission, gamma-ray bursts, and solar flares are planned.
    Keywords: ASTRONOMY
    Type: Space Science Reviews (ISSN 0038-6308); 49; 1-2,
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  • 13
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    Unsteady transonic flow simulation on a full-span-wing-body configuration (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 1450-145
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  • 14
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    Unsteady transonic aerodynamics and aeroelastic calculations at low-supersonic freestreams (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A computational procedure is presented to simulate transonic unsteady flows and corresponding aeroelasticity of wings at low-supersonic freestreams. The flow is modeled by using the transonic small-perturbation theory. The structural equations of motions are modeled using modal equations of motion directly coupled with aerodynamics. Supersonic freestreams are simulated by properly accounting for the boundary conditions based on pressure waves along the flow characteristics in streamwise planes. The flow equations are solved using the time-accurate, alternating-direction implicit finite-difference scheme. The coupled aeroelastic equations of motion are solved by an integration procedure based on the time-accurate, linear-acceleration method. The flow modeling is verified by comparing calculations with experiments for both steady and unsteady flows at supersonic freestreams. The unsteady computations are made for oscillating wings. Comparisons of computed results with experiments show good agreement. Aeroelastic responses are computed for a rectangular wing at Mach numbers ranging from subtransonic to upper-transonic (supersonic) freestreams. The extension of the transonic dip into the upper transonic regime is illustrated.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 955-961
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  • 15
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    Further comparisons of interactive boundary-layer and thin-layer Navier-Stokes procedures (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 897-903
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  • 16
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    Transonic Navier-Stokes solutions for a fighter-like configuration (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 875-881
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  • 17
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    Zodiacal emission. I - Dust near the earth's orbit (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The infrared emission of interplanetary dust near the earth's orbit is derived from IRAS observations of the gradient of in-ecliptic brightness tangent to the earth's orbit, and the annual variation of the ecliptic polar brightness. Models with five grain constituents and three size distributions are compared with the observations. The observed emission is twice as bright as predicted; this discrepancy is due either to calibration errors or to enhanced radiative efficiency of 'fluffy' particles. Graphite and magnetite particles are ruled out because they are too hot. The size distribution is constrained to be less steep than that derived from lunar microcrater studies, and is consistent with that obtained by earth-orbiting satellites. Nonhomogeneous silicate grains with 3 percent graphite impurity produce the best fit to the spectrum. The model predictions extend from 3 microns to 1 mm, for use in analyzing future infrared background observations.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 335; 468-485
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  • 18
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    The dynamics of coorbital satellite systems (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The dynamical behavior of N coorbital satellites moving with the same average mean motion around a primary has been studied both analytically and by numerical integrations for N from 2 to 9 satellites. Simplified dynamical equations are used to determine the different stationary configurations and their local stability against infinitesimal perturbations. The ring of equally spaced identical satellites is found to be locally unstable for N of six or less, while for N from two to eight there exists another stable compact stationary configuration with separations of 60 deg or less between adjacent satellites. For N of seven or more the equally spaced configuration becomes locally stable, and for N of nine or more it is the only stationary configuration. The motion becomes chaotic for large-amplitude perturbations. The chaotic motion fills a restricted region of phase space whose outer boundary is determined by the maximum velocity curve.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 205; 1-2,; 309-327
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  • 19
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    Infrared photometry of Comet P/Halley pre- and post-perihelion (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Infrared photometry of Comet P/Halley is presented over a period ranging from September 1985 to June 1986, prehelion and posthelion. Short-term variations are observed in the intervals Dec. 25, 1985 - Jan. 3, 1986 and Feb.17 - March 3, 1986. When the comet is in a quiescent state, the infrared flux increases linearly with the diaphragm size, which implies a dust expansion at constant velocity up to a distance to the nucleus of at least 10,000 km. The temperature measured in April 1986 ranges between 250 and 300 K, in reasonable agreement with the expected equilibrium temperature of the grains. Between September 1985 and June 1986, no evidence of variation in the dust nature is observed.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 205; 1-2,; 301-308
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  • 20
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    Differential imaging of forbidden Fe X in IC 443 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper presents images of two areas of the supernova remnant IC 443 showing emission from the forbidden 6374 A red coronal line taken with an emission-line differential imaging camera. The areas are in the vicinity of strong soft X-ray emission as observed with the Einstein Observatory. The forbidden Fe X emission is patchy on the scale of seconds of arc. For the brightest emission regions, an electron density of approximately 60/cu cm and gas pressures of 0.l7 x 10 to the 8th/cu cm K are found. These estimates are speculative because of the large correction for interstellar dust, and the assumption of sheetlike structure. Although this region has the highest average surface brightness, no direct correlation is found between the X-ray and forbidden Fe X knots. The implied physical conditions in the region suggest that the forbidden Fe X knots are being evaporated.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 334; 852-861
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  • 21
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    Experimental aerodynamic characteristics of an NACA 0012 airfoil with simulated glaze ice (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effect of a simulated glaze-ice accretion on the aerodynamic performance of a NACA 0012 airfoil was studied experimentally. Two ice shapes were tested: one from an experimentally measured accretion, and one from an accretion predicted using a computer model given the same icing conditions. Lift, drag, and pitching moment were measured for the airfoil with both smooth and rough ice shapes. The ice shapes caused large lift and drag penalties, primarily due to large separation bubbles. Surface pressure distributions clearly showed the regions of separated flow. The aerodynamic performance of the two shapes compared well at positive, but not negative, angles of attack.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 849-854
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  • 22
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    Grid generation and inviscid flow computation about a cranked-winged airplane geometry (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 820-826
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  • 23
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    Tidal interactions and infrared-bright QSOs (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Deep direct images of five IRAS-selected QSOs with similar IR luminosities and spectral indices have been analyzed. The present objects possess IR luminosities similar to those of the IRAS flux-lined sample of ultraluminous galaxies, but have IR spectral indices similar to those of normal QSOs. Four of the objects are in strong tidal interaction and have blue host galaxies and reddened nuclei. It is suggested that these objects are QSOs and AGN in an intermediate stage of their activity, which lies between that of ultraluminous galaxies and optically selected QSOs.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 96; 1575-158
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  • 24
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    Nature of dust grains in comets (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The observed reddening in the wavelength range 0.26-2.25 microns for comae of several comets can be represented quite well with model grains having real and imaginary parts of refractive index, m = m-prime - im-double prime, given by m-prime of about 1.38 and m-double prime of about 0.039, respectively. It is also possible to explain the observations of linear polarization and geometric albedo of comet comae.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 233; 573-579
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  • 25
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    A large family of compact radio sources in the starburst nucleus of NGC 253 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Deep VLA maps of NGC 253 show that it has at least 35 compact radio sources similar to those in the prototypical IR starburst galaxy M82. It is noted that NGC 253 is a twin of M82 in IR spectrum and luminosity as well as distance. Some of the sources in M82 which are rapidly expanding and fading are believed to be extremely young supernova remnants. Most of the sources detected in NGC 253 are unresolved or only marginally resolved, with typical diameters no greater than 2-5 pc. If they are young supernova remnants expanding at 12,000 km/s, the source ages are no more than 160-400 yr. This requires a supernova rate of about 1/0.1 yr. If the compact radio sources are indeed young supernova remnants, star formation must have ceased shortly after the progenitors of the current supernovae were produced.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 330; L97-L100
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  • 26
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    Effects of surface roughness on two Shuttle Orbiter models (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 349-354
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  • 27
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    Thermal environment of transatmospheric vehicles (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 355-363
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  • 28
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    Unsteady low-speed aerodynamic model for complete aircraft configurations (1988)
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 302-310
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  • 29
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    Outcomes of planetary close encounters - A systematic comparison of methodologies (1988)
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    Publication Date: 2011-08-19
    Description: Several methods for estimating the outcomes of close planetary encounters are compared on the basis of the numerical integration of a range of encounter types. An attempt is made to lay the foundation for the development of predictive rules concerning the encounter outcomes applicable to the refinement of the statistical mechanics that apply to planet-formation and similar problems concerning planetary swarms. Attention is given to Oepik's (1976) formulation of the two-body approximation, whose predicted motion differs from the correct three-body behavior.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 75; 1-29
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  • 30
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    A radial-velocity survey of the Hyades (1988)
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    Publication Date: 2011-08-19
    Description: Photoelectric radial-velocity measurements, obtained with external error as small as 0.1 km/s using the 200-inch Hale telescope at Palomar Observatory during the period 1971-1986, are reported for over 400 candidate members (with V magnitude between 6 and 14) of the Hyades cluster. The history of Hyades observations is recalled; the Palomar instrumentation and observing program are described; the data-reduction and standardization procedures are discussed in detail; and the data are presented in extensive tables and graphs. About 200 of the stars are classified as cluster members, including 60 spectroscopic binaries.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 96; 172-197
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  • 31
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    A new convergent point and distance modulus for the Hyades from radial velocities (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The dynamics of the Hyades open star cluster is investigated analytically on the basis of the photoelectric radial velocities reported by Griffin et al. (1988). The methods used to determine the radial-velocity gradient, convergent point, and distance modulus are described, and the results are presented in tables and graphs and characterized in detail. Findings reported include convergent-point alpha = 98.2 + or - 1.1 deg and delta = 6.1 + or - 1.0 deg, space motion 48.0 + or - 0.27 km/s, distance to cluster center 45.4 + or - 2.1 pc, distance modulus 3.28 + or - 0.10, and cluster velocity dispersion 230 m/s.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 96; 198-210
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  • 32
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    Passive venting system for modifying cavity flowfields at supersonic speeds (1988)
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    Publication Date: 2011-08-19
    Description: The drag of airfoils in transonic flow can be reduced through the use of a passive venting system that employs a porous plate for part of the airfoil upper surface with a vent chamber underneath the porous plate Attention is given to the results obtained with a wind tunnel model employing such a porous floor system. This passive venting system has been used to extend the length/height value before the onset of high drag-producing closed cavity flow at supersonic speeds.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 374-376
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  • 33
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    Vortex shedding in high-speed compressor blade wakes (1988)
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    Publication Date: 2011-08-19
    Description: The wakes of highly loaded compressor blades are generally considered to be turbulent flows. Recent work has suggested that the blade wakes are dominated by a vortex streetlike structure. The experimental evidence supporting the wake vortex structure is reviewed. This structure is shown to redistribute thermal energy within the flowfield. The effect of the wake structure on conventional aerodynamic measurements of compressor performance is noted. A two-dimensional, time-accurate, viscous numerical simulation of the flow exhibits both vortex shedding in the wake and a lower-frequency flow instability that modulates the shedding. The numerical results are shown to agree quite well with the measurement from transonic compressor rotors.
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 4; 236-244
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  • 34
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    IRAS observations of galaxies in the Virgo cluster area (1988)
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    Publication Date: 2011-08-19
    Description: IRAS data on 196 galaxies in the area of the Virgo Cluster are presented. The data derive from combining all available survey observations for each object and therefore achieve greater sensitivity than the IRAS Point Source Catalog (PSC). The enhanced sensitivity allows 78 galaxies to be detected at 12 microns, 82 at 25 microns, 139 at 60 microns, and 135 at 100 microns, compared to 16, 23, 88, and 95 detections listed in the PSC. From the blue compact dwarf galaxy sample, 23 and 19 objects are detected at 60 and 100 microns, compared to three and two detections listed in the PSC. The emission in three close pairs of galaxies which are reported as single sources in the PSC are separated here. These statistics demonstrate the importance and potential of a detailed examination of IRAS data, especially for possibly resolved sources and, in particular, for galaxies out to redshifts of 0.008 or galaxies with D(25) of 3 arcmin or greater.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 68; 151-172
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    A catalog of IRAS observations of large optical galaxies (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A catalog is presented of IRAS observations of 85 galaxies with blue-light isophotal diameters greater than 8 arcmin. The observations, data processing, and data measurement techniques are described, and total IRAS flux densities and integrated infrared emission properties of the sample are reported. Infrared brightness profiles of the detected galaxies and infrared surface brightness contour maps of the galaxies for which structural features were resolved are displayed. A classification scheme based on the degree of central concentration and spatial structure of the 60 micron emission of the best-resolved galaxies is proposed. The 60 micron and blue-light isophotal diameters of the largest galaxies are compared.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 68; 91-127
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  • 36
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    The detection of a discrete outflow from the young stellar object GL 490 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A high-resolution (0.059/cm) M-band spectrum has been obtained of the embedded young stellar object GL490. The spectrum shows interstellar absorption in the fundamental vibrational band, v = 1-0, of (C-12)O. Two strong and narrow (10 km/s) velocity components are present. One, at the velocity of GL490 (vLSR = -16 km/s), is likely gas in the molecular cloud within which GL490 is embedded. The other component is blueshifted by 13 km/s relative to GL490. An observation of emission from the J = 3-2 transition of HCO(+) using a 20-arcsec beam supports the view that the blueshifted gas is near the central object. The -29-km/s feature is interpreted as a recently ejected shell. It is conjectured that the extended outflows of cold molecular gas seen by millimeter CO emission observations are driven by sporadic outbursts rather than by continuous flows from the central object.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 201; 1, Ju; L16-L18
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  • 37
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    Prediction of oscillating thick cambered aerofoil aerodynamics by a locally analytic method (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The effects of mean-flow incidence, airfoil camber, and airfoil thickness on the incompressible aerodynamics of an oscillating airfoil are investigated theoretically, developing and applying a first-order FEM based on locally analytical solutions (LASs). Laplace equations are used to describe the steady and unsteady harmonic velocity potentials; a body-fitted computational grid is employed; grid-element solutions for both potentials are determined using a numerical LAS method; and the LASs are then assembled to obtain a complete solution. Results for a series of flat-plate and Joukowski airfoils are presented in extensive graphs and discussed in detail.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 8; 913-931
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  • 38
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    Astronomy and astrophysics with the Advanced X-ray Astrophysics Facility (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The optics and instruments of the Advanced X-ray Astrophysics Facility (AXAF) are described. The instrument capabilities are reviewed so that potential users of AXAF may plan supporting research in the years prior to launch. The AXAF is to be built around a large-area high-resolution grazing-incidence X-ray telescope, with a complement of imaging and spectroscopic instruments which can be maintained and/or replaced in orbit. An important feature of the AXAF is the aspect system. It utilizes solid state star cameras and fiducial lights to permit both image reconstruction (on the ground) with minimal blurring due to spacecraft and internal motions, and placement of the X-ray image on the sky to an accuracy of 1 arcsec.
    Keywords: ASTRONOMY
    Type: Space Science Reviews (ISSN 0038-6308); 47; 1-2,
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  • 39
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    Computer analysis of some ancient Chinese sunrise eclipse records to determine the earth's rotation rate (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: ASTRONOMY
    Type: Vistas in Astronomy (ISSN 0083-6656); 31; 833-847
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  • 40
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    Multigrid solution of the two-dimensional Euler equations on unstructured triangular meshes (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 824-831
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  • 41
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    Multigrid acceleration of the flux-split Euler equations (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 649-654
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  • 42
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    Vortical flow over an elliptical-body missile at high angles of attack (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 25; 24-30
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  • 43
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    Model-independent constraints on possible modifications of Newtonian gravity (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New model-independent constraints on possible modifications of Newtonian gravity over solar-system distance scales are presented, and their implications discussed. The constraints arise from the analysis of various planetary astrometric data sets. The results of the model-independent analysis are then applied to set limits on a variation in the l/r-squared behavior of gravity, on possible Yukawa-type interactions with ranges of the order of planetary distance scales, and on a deviation from Newtonian gravity of the type discussed by Milgrom (1983).
    Keywords: ASTRONOMY
    Type: Physical Review Letters (ISSN 0031-9007); 61; 1159-116
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  • 44
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    On the redistribution of OB star luminosity and the warming of nearby molecular clouds (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: IRAS observations of the neighborhoods of six H II regions in the outer Galaxy are correlated with CO maps of the same regions. It is found that more than half of the far-IR luminosity from within about 25 to 75 pc of the ionizing stars is contributed by dust associated with molecular clouds. It is shown that a major and increasing fraction of the OB cluster starlight is not absorbed locally. The observations suggest that the H II regions are not radiation-bounded and have ion densities of about 1/cu cm. A model describing the interstellar environment of OB star clusters as a function of time is presented.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 332; 954-963
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  • 45
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    Spectrophotometry of Wolf-Rayet stars - Intrinsic colors and absolute magnitudes (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Absolute spectrophotometry of about 10-A resolution in the range 3400-7300 A have been obtained for southern Wolf-Rayet stars, and line-free magnitudes and colors have been constructed. The emission-line contamination in the narrow-band ubvr systems of Westerlund (1966) and Smith (1968) is shown to be small for most WN stars, but to be quite significant for WC stars. It is suggested that the more severe differences in intrinsic color from star to star of the same spectral subtype noted at shorter wavelengths are due to differences in atmospheric extent. True continuum absolute visual magnitudes and intrinsic colors are obtained for the LMC WR stars. The most visually luminous WN6-WN7 stars are found to be located in the core of the 30 Doradus region.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 96; 1076-109
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  • 46
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    Theory of idealized two-dimensional ballute in Newtonian hypersonic flow (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 25; 217-224
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  • 47
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    Phobos and Deimos astrometric observations from Viking (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This article describes the reduced astrometric observations of Phobos and Deimos derived from Viking Orbiter 1 and 2 imaging data. This data set spans four years from 1976 to 1980, contains 275 sets of spacecraft-centered, right ascension and declination observations, and has a limiting accuracy of a few km (1 sigma). The details of observation formulation and use for ephemeris improvement are given.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 201; 1, Ju
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  • 48
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    Planet X - Fact or fiction? (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The search for a possible tenth planet in our solar system is examined. The history of the discoveries of Uranus, Neptune, and Pluto are reviewed. Searches of the sky with telescopes and theoretical studies of the gravitational influences on the orbits of known objects in the solar system are discussed. Information obtained during the Pioneer 10 and 11 missions which could suggest the presence of an undiscovered planet and computer simulations of the possible orbit of a tenth planet are presented.
    Keywords: ASTRONOMY
    Type: Planetary Report (ISSN 0736-3680); 8; 6-9
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  • 49
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    The dwarf nova dippers (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Previous papers have shown that the dwarf nova OY Car has an extensive vertical disk structure during its superoutbursts. This structure is analogous to that seen in the low mass X-ray binaries (LMXBs), in that the whole disk flares toward its edge, and there is a bulge or 'dark spot' where the mass transfer stream meets the disk edge. The paper presents evidence suggesting that two more dwarf novae may have such a stream impact bulge, which manifests itself as a dip in the UV light curve, analogous to those seen in the X-ray light curves of the LMXB dippers.
    Keywords: ASTRONOMY
    Type: Advances in Space Research (ISSN 0273-1177); 8; 2-3,
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  • 50
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    The C IV doublet ratio intensity effect in symbiotic stars (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: High-resolution UV spectra in the 1200-2000 wavelength range of the symbiotic variable R Aqr and its nebular jet were obtained in July 1987 with the IUE. The line profile structure of the C IV 1548, 1550 doublet in the jet indicates multicomponent velocity structure from an optically thin emitting gas. The C IV doublet profiles in the compact H II region engulfing the Mira and hot companion binary also suggest multicomponent structure with radial velocities up to about -100 km/s. The value of the doublet intensity ratio in the R Aqr H II region has been observed in other similar symbiotic stars, such as RX Pup. It is suggested that the anomalous behavior of the C IV doublet intensities may be useful for studying the spatial structure and temporal nature of winds in symbiotic stars.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 331; 477-485
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  • 51
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    Incompressible Navier-Stokes computations for a round-edged double-delta wing (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 675
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  • 52
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    Transonic characteristics of a humped airfoil (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 673
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  • 53
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    Resolution of the circumstellar disk of Beta Pictoris at 10 and 20 microns (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations at 10 and 20 microns with about 5 arcsec resolution are presented of the central, approximately 13 arcsec diameter region of the A5 dwarf Beta Pictoris. These observations resolve the inner disk and provide important constraints for models of the star and a basis for removing some of their ambiguities. The evidence indicates that submicron-sized grains emit much of the excess 10 and 20 micron radiation from the star. The characteristics of the dust are discussed, and the possibility that comets form the dust reservoir is considered.
    Keywords: ASTRONOMY
    Type: Nature (ISSN 0028-0836); 335; 51-53
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  • 54
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    Prediction of incidence effects on oscillating airfoil aerodynamics by a locally analytical method (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A complete mathematical model is formulated to analyze the effects of mean-flow incidence angle on the unsteady aerodynamics of an oscillating airfoil in an incompressible flow field. A velocity potential formulation is utilized. The steady flow is independent of the unsteady flow field but coupled to it through the boundary conditions on the oscillating airfoil. The numerical solution technique for both the steady and unsteady flow fields is based on a locally analytical method. The flow model and solution method are then verified through the excellent correlation obtained with the Theodorsen oscillating-flat-plate and Sears transverse-gust classical solutions. The effects of mean flow incidence on the steady and oscillating airfoil aerodynamics are then investigated.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Engineering (ISSN 0029-5981); 26; 2227-223
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  • 55
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    Efficient algorithm for solution of the unsteady transonic small-disturbance equation (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 25; 598-605
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  • 56
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    Study of multibody aerodynamic interference at transonic Mach numbers (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 553-560
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  • 57
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    Accurate radio and optical positions for the radio star HD 36705 (AB Doradus) (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Arc-second position measurements of the active star HD 36705 (AB Dor) and of the variable radio source found nearby are presented. These measurements show that the radio source is clearly identified with HD 36705 and not with the nearby red-dwarf star Rst 137B.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 100; 825-827
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    A thin-layer solution of the flow about a prolate spheroid (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Computational results are presented for the transitional or turbulent flow about a prolate spheroid, at alpha = 10 deg or 30 deg, correspondingly, using an implicit, approximately factored, partially flux-split algorithm, based on the thin-layer equations. The computed flow field is in good agreement with available experimental data.
    Keywords: AERODYNAMICS
    Type: Zeitschrift fuer Flugwissenschaften und Weltraumforschung (ISSN 0342-068X); 12; 173-180
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    The high-latitude F supergiant IRAS 18095 + 2704 - A proto-planetary nebula (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The paper reports the discovery of a new high-latitude F supergiant, IRAS 18095 + 2704, which shows a large excess in the far-infrared. Ground-based observations have identified it as a V = 10.4 mag F3 Ib star which displays light and velocity variability. Comparison with the post-asymptotic giant branch (AGB) evolution model of Volk and Kwok suggests that it is an excellent candidate for a protoplanetary nebula. Model fitting of the spectrum of 18095 + 2704 from 0.35 to 100 microns suggests that it evolved from the AGB approximately 265 yr ago and had a mass-loss rate of 0.00003 solar mass/yr at the end of the AGB.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 331; 832-837
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    Molecular clouds in the Carina arm - The largest objects, associated regions of star formation, and the Carina arm in the Galaxy (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Columbia CO survey of the southern Galactic plane is used to identify giant molecular clouds and cloud complexes in the Vela-Carina-Centaurus section of the Galaxy. Twenty-seven giant molecular clouds between l = 270 and 300 deg are catalogued and their heliocentric distances given. In addition, 16 clouds at l greater than 300 deg beyond the solar circle extend the catalog to include the very distant portion of the Carina arm. The most massive clouds in the catalog trace the Carina arm over 23 kpc in the plane of the Galaxy. The average mass of these objects is 1.4 x 10 to the 6th solar, and their average spacing along the arm is 700 pc. The composite distribution projected onto the Galactic plane of the largest molecular clouds in the Carina arm and of similarly massive clouds in the first and second quadrants strongly suggests that the Carina and Sagittarius arms form a single spiral arm about 40 kpc in length wrapping two-thirds of the way around the Galaxy. Descriptions of each cloud, including identification of associated star-forming regions, are presented in an appendix.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 331; 181-196
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    Turbulent viscous drag reduction with thin-element riblets (1988)
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    Publication Date: 2011-08-19
    Description: Thin-element riblets for aircraft aerodynamic surface turbulent viscous drag reduction are presently found to be as effective as symmetric V-grooves in this role, while possessing a greater range of admissible spacings. The thin-element geometry shows the qualitatively predictable influence of independent riblet height and spacing variations. The evidence for more than one drag-reduction mechanism in thin-element riblets is found to be inconclusive.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 496-498
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    Rarefaction effects for hypersonic re-entry flow (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 26; 392
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    An overview of hypersonic aerothermodynamics (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This paper briefly reviews some national studies and new programs concerning hypersonic flight. The flight environment that will be encountered by this new class of hypersonic vehicles is described, and the fluid-dynamic and chemical phenomena that occur in hypersonic flight are examined. Ground-based facilities are briefly described, and their use in helping to validate the codes is examined.
    Keywords: AERODYNAMICS
    Type: Communications in Applied Numerical Methods (ISSN 0748-8025); 4; 319-325
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    Faint blue objects at high Galactic latitude. V - Palomar Schmidt field centered on selected area 71 (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Starlike objects with both blue and ultraviolet excess have been selected from a Palomar 1.2 m Schmidt field centered on Kapteyn selected area 71. The method of selection is that used in the previous papers of this series, but modified to account for the differential reddening that occurs across the field. The color classes, color subclasses, positions, and magnitudes of the selected objects are listed.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 66; 1-18
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    Entropy and vorticity corrections for transonic flows (1988)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Different models for inviscid transonic flows are examined. The common assumptions that the flow is isentropic and irrotational are critically evaluated. Entropy and vorticity correction procedures for potential and stream function formulations are presented, together with the details of the treatment of shocks and wakes, and drag and lift calculations. The non-uniqueness problem of the potential formulation is studied using different artificial viscosity forms. Numerical results are compared with Euler solutions.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 8; 31-53
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    Drag measurements on a laminar flow body of revolution in Langley's 13 inch magnetic suspension and balance system (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Low-speed wind tunnel drag force measurements were taken on a laminar flow body of revolution free of support interference. This body was tested at zero incidence in the NASA Langley 13 inch Magnetic Suspension and Balance System (MSBS). The primary objective of these tests was to substantiate the drag force measuring capabilities of the 13 inch MSBS. A secondary objective was to obtain support interference free drag measurements on an axisymmetric body of interest. Both objectives were met. The drag force calibrations and wind-on repeatability data provide a means of assessing the drag force measuring capabilities of the 13 inch MSBS. The measured drag coefficients for this body are of interest to researchers actively involved in designing minimum drag fuselage shapes. Additional investigations included: the effects of fixing transition; the effects of fins installed in the tail; surface flow visualizations using both liquid crystals and oil flow; and base pressure measurements using a one-channel telemetry system. Two drag prediction codes were used to assess their usefulness in estimating overall body drag. These theoretical results did not compare well with the measured values because of the following: incorrect or non-existent modeling of a laminar separation bubble on the body and incorrect of non-existent estimates of base pressure drag.
    Keywords: AERODYNAMICS
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    Optimization of slender wings for center-of-pressure shift due to change in Mach number (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: It is observed that the center of pressure on a wing shifts as the Mach number is changed. Such shifts are in general undesirable and are sometimes compensated for by actively shifting the center of gravity of the aircraft or by using active stability controls. To avoid this complication, it is desirable to design the wings of a high speed aircraft so as to minimize the extent of the center-of-pressure shifts. This, together with a desire to minimize the center-of-pressure shifts in missile control surfaces, provides the motivation for this project. There are many design parameters which affect center-of-pressure shifts, but it is expected that the largest effects are due to the wing planform. Thus, for the sake of simplicity, this study is confined to an investigation of thin, flat, (i.e., no camber or twist), relatively slender, pointed wings flying at a small angle of attack. Once the dependence of the center of pressure on planform and Mach number is understood, we can expect to investigate the sensitivity of the center-of-pressure shifts to various other parameters.
    Keywords: AERODYNAMICS
    Type: Hampton Inst., NASA/American Society for Engineering Educ; Hampton Inst., NASA(
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    Comparison of the 3.36 micrometer feature to the ISM (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: It has been noted that the 3.36 micrometer emission feature is not the same as that of any ISM band at 3.4 micrometer. This is documented herein. There is no convincing analog to the cometary 3.36 micrometer emission feature seen in the Interstellar Matter band. This fact suggests that if the carbonaceous material in comets came from the ISM, it was either further processed in the solar nebula or has a different appearance because of the different excitation environment of the sun and ISM.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 79-82
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    A comparison of Halley dust with meteorites, interplanetary dust and interstellar grains (1988)
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    Publication Date: 2013-08-31
    Description: The variability of the mineral forming elements in the submicron Halley grains provides a powerful basis for comparison of Halley with the different classes of meteoritic materials that have been studied in the lab. The degree of variability in the Halley samples is larger than that seen in chondrites implying that Halley is more heterogeneous at the submicron scale. A critical distinction is that Halley contains abundant pure Mg silicates at the size scale while the carbon rich meteorites do not. The submicron dispersion composition seen in Halley is dramatically different from the narrowly constrained compositions seen in CI and CM (type 1 and 2) carbonaceous chondrites. These meteorites are carbon rich but are dominated by a hydrated silicate with a very narrow range of Mg/Si ratio. The Halley results are also unlike the composition variations seen in most of interplanetary dust types that are dominated by hydrated materials. The only known class of meteoritic material that appear to closely resemble the Halley data is a class of cosmic dust composed entirely of anhydrous minerals. The composition implies that Halley is dominated by olivine, pyroxene, iron sulfide, glass and amorphous carbonaceous matter.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 66-67
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  • 70
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    Moisture adsorption in optical coatings (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The thin film filter is a very large aperture component which is exceedingly useful because of its small size, flexibility and ease of mounting. Thin film components, however, do have defects of performance and especially of stability which can cause problems in systems, particularly where long-term measurements are being made. Of all of the problems, those associated with moisture absorption are the most serious. Moisture absorption occurs in the pore-shaped voids inherent in the columnar structure of the layers. Ion-assisted deposition is a promising technique for substantially reducing moisture adsorption effects in thin film structures.
    Keywords: ASTRONOMY
    Type: NASA, Ames Research Center, Second Workshop on Improvements to Photometry; p 303-320
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  • 71
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    Infrared observations of the dust coma (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The main infrared observational results were briefly reviewed at the start of this session. The new results are summarized. All of these results have yet to be synthesized into a self-consistent picture of the dust grain composition, dust production history, outburst mechanisms, and composition of the nucleus. The workshop discussion was helpful in pointing out problems faced by theorists, such as data quality, the lack of the proper theory for computing the scattering and emission of irregular particles, and in some cases the lack of optical constants of realistic materials. It is expected that the gross spectral and dynamical properties of Halley's Comet can be understood in time, even if the details of the observations and the theoretical calculations continue to vex us in the future.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 1-21
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  • 72
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    Fiber optic wavelength division multiplexing: Principles and applications in telecommunications and spectroscopy (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Design and fabrication tradeoffs of wavelength division multiplexers are discussed and performance parameters are given. The same multiplexer construction based on prism gratings has been used in spectroscopic applications, in the wavelength region from 450 to 1600 nm. For shorter wavelengths down to 200 nm, a similar instrument based on longer fibers (500 to 1000 micrometer) has been constructed and tested with both a fiber array and a photodiode detector array at the output.
    Keywords: ASTRONOMY
    Type: NASA, Ames Research Center, Second Workshop on Improvements to Photometry; p 255-276
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  • 73
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    Absolute photometric calibration of detectors to 0.3 mmag using amplitude-stabilized lasers and a helium-cooled absolute radiometer (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Laser sources whose intensity is determined with a cryogenic electrical substitution radiometer are described. Detectors are then calibrated against this known flux, with an overall error of 0.028 percent (0.3 mmag). Ongoing research has produced laser intensity stabilizers with flicker and drift of less than 0.01 percent. Recently, the useful wavelength limit of these stabilizers have been extended to 1.65 microns by using a new modular technology and InGaAs detector systems. Data from Si photodiode calibration using the method of Zalewski and Geist are compared against an absolute cavity radiometer calibration as an internal check on the calibration system.
    Keywords: ASTRONOMY
    Type: NASA, Ames Research Center, Second Workshop on Improvements to Photometry; p 153-178
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  • 74
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    Optical and electrical measurements on UV sensitive photodiodes (1988)
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    Publication Date: 2013-08-31
    Description: The optical and electrical characteristics of the various types of photodiodes potentially useful for UV radiometers were studied. It was concluded that both GaAsP and GaP photodiodes have advantages over silicon photodiodes in terms of spectral response and UV stability. Both GaAsP and GaP have excellent electrical characteristics for low frequency radiometers, although their high capacitance could be inconvenient for high frequency applications. GaAsP is particularly good with respect to dynamic range.
    Keywords: ASTRONOMY
    Type: NASA, Ames Research Center, Second Workshop on Improvements to Photometry; p 85-109
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  • 75
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    Application of PN and avalanche silicon photodiodes to low-level optical (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: New approaches to the discovery of other planetary systems require very sensitive and stable detection techniques in order to succeed. Two methods in particular, the astrometric and the photometric methods, require this. To begin understanding the problems and limitations of solid state detectors regarding this application, preliminary experiments were performed at the National Bureau of Standards and a low light level detector characterization facility was built. This facility is briefly described, and the results of tests conducted in it are outlined. A breadboard photometer that was used to obtain stellar brightness ratio precision data is described. The design principles of PN and avalanche silicon photodiodes based on low light level measuring circuits are discussed.
    Keywords: ASTRONOMY
    Type: NASA, Ames Research Center, Second Workshop on Improvements to Photometry; p 111-151
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  • 76
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    Analog-to-digital conversion techniques for precision photometry (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Three types of analog-to-digital converters are described: parallel, successive-approximation, and integrating. The functioning of comparators and sample-and-hold amplifiers is explained. Differential and integral linearity are defined, and good and bad examples are illustrated. The applicability and relative advantages of the three types of converters for precision astronomical photometric measurements are discussed. For most measurements, integral linearity is more important than differential linearity. Successive-approximation converters should be used with multielement solid state detectors because of their high speed, but dual slope integrating converters may be superior for use with single element solid state detectors where speed of digitization is not a factor. In all cases, the input signal should be tailored so that they occupy the upper part of the converter's dynamic range; this can be achieved by providing adjustable gain, or better by varying the integration time of the observation if possible.
    Keywords: ASTRONOMY
    Type: NASA, Ames Research Center, Second Workshop on Improvements to Photometry; p 179-192
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  • 77
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    The NASA Infrared Telescope Facility Comet Halley monitoring program 2: Post-perihelion results (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The post perihelion results of a 1 to 20 micrometer infrared monitoring program of Comet Halley are presented. These results complement previous observations of the pre-perihelion passages of Halley. The observations cover the time period of Mar. 1986 to the present time. During the time the comet was observable, two or more observations were obtained per month. The most interesting results were: (1) a detectable change in the J-H and H-K colors of Halley, and (2) a search for a nucleus rotation at J during 20 Feb. to 10 Mar. was unsuccessful. The perihelion J-H and K-K colors were constant at 0.48 + or - 0.01 and 0.17, respectively. A preliminary reduction of the data is given. It is concluded that the colors were at first similar to pre-perihelion and then changed from July onward to be bluer and more similar to the solar colors. This suggests that a change may have occurred in the composition of the dust coma of Halley in July 1986.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 186
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  • 78
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    Light scattering of large rough particles application to cometary grains (1988)
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    Publication Date: 2013-08-31
    Description: While the electromagnetic field scattered by a spherical particle is classically obtained by the Helmholtz equation, the general case of an arbitrary particle may be investigated in the general framework of the interaction of a wave with a scattering potential. A wave function then satisfies the Schroedinger equation. The general solution of the Schroedinger equation is given. The main disadvantage of this approach are its restriction to large particles and its scalar nature preventing the calculation of the polarization. However, Perrin and Lamy have shown how to avoid the second limitation and retrieve a vectorial description. They proved that in the case of large spheres when the ad hoc assumptions are satisfied, the expression of the scattering amplitude may be approximated by an expansion series in partial waves, i.e., on a discrete basis. The analogy may be generalized, and the ratio of the two components for a rough particle obtained by taking the ratio of the reflectivities for the two directions of polarization. These reflectivities involve the simple and double reflections calculated following the method developed by Wolff for rough surfaces. The theory is further detailed.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 156-157
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  • 79
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    Airborne 20-65 micron spectrophotometry of Comet Halley (1988)
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    Publication Date: 2013-08-31
    Description: Observations of Comet Halley with a grating spectrometer on board the Kuiper Airborne Observatory on four nights in Dec. 1985 to Apr. 1986 are reported. Low resolution 20 to 65 micrometer spectra of the nucleus with a 40 arcsec FWHM beam was obtained on 17 Dec. 1985, and on 15 and 17 Apr. 1986. On 20 Dec. 1985, only a 20 to 35 micrometer spectrum was obtained. Most of the data have been discussed in a paper where the continuum was dealt with. In that paper, models were fit to the continuum that showed that more micron sized particles of grain similar to amorphous carbon were needed to fit the spectrum than were allowed by the Vega SP-2 mass distribution, or that a fraction of the grains had to be made out of a material whose absorption efficiency fell steeper than lambda sup -1 for lambda greater than 20 micrometers. Spectra was also presented taken at several points on the coma on 15 Apr. which showed that the overall shape to the spectrum is the same in the coma. Tabulated values of the data and calibration curves are available. The spectral features are discussed.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 147-149
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  • 80
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    The problem of clustering in laboratory studies of cometary dust (1988)
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    Publication Date: 2013-08-31
    Description: In trying to understand the nature of interstellar or interplanetary dust grains it is tempting to simply rely on direct lab measurements of grain properties such as extinction. However, until agreement is achieved between directly measured extinction and the same property calculated from measured optical constants of the solid, application to astronomical observations is questionable. There are two major problems which are discussed: the problem of what optical constants to use in the calculation, and the almost unavoidable problem of particle clustering in lab studies. Regarding small particle measurements, a problem afflicting almost all lab measurements is the clustering of particles. Having failed in efforts to isolate particles, the solution to the problem was attempted with a simple theory which seems to adequately describe the extinction by small, clustered particles in many cases. The theory is briefly explained.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 154-155
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  • 81
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    Infrared observations of P/Halley and P/Encke (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Broadband optical/infrared photometers responding from 0.5 to 23 microns mounted on the Univ. of Minnesota (UM) O'Brien 76-cm telescope, Wyoming Infrared Observatory 234-cm telescope, and UM's Mount Lemmon Infrared Observatory 152-cm telescope were used to measure comet Halley more than 30 times between 12 Dec. 1985 to 6 May 1986. The Wyoming system was used to measure P/Encke on 24 Jul. 1987. The equipment and observations of Halley were fully described by Gehrz and Ney. Conclusions based on a preliminary analysis of the Halley and P/Encke data are reported.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 145-146
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  • 82
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    The near-infrared polarization and color of Comet Halley: What can we learn about the grains (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The near infrared polarization and JHK colors of light scattered by dust grains in comet Halley were measured over a wide range in phase angle and heliocentric distance. Colors were redder than solar with no statistically significant variation with phase angle, heliocentric distance, or pre- and post-perihelion. This suggests that the grain population did not change drastically over time and that the data may be combined and modeled. However, short term variations in visible polarization and dust albedo were seen in Halley. Also, near infrared colors became systematically bluer after the observations were completed. The near infrared colors of Halley fall in the range of those of other comets. The near infrared polarization is similar to the visible polarization of Halley and other comets in showing a negative branch at small phase angles and an approximately linear rise toward positive values at larger phase angles. Mie theory calculations and a size distribution based on spacecraft data were used to model the near infrared polarization and color of comet Halley. Numerous lines of evidence point to the presence of dark, absorbing, probably carbonaceous materials in comets.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 134-135
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  • 83
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    The spectral appearance of comets from 5 to 20 micrometers: A survey of the data (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Based on the concept of comets as being conglomerates of rocks and ices, it is expected that they reflect these components in their emission spectra. Silicate materials (rocks) are common in many astronomical environments and show prominent features at about 10 and 18 micrometers. Carbon should be abundant, but is much more difficult to detect spectroscopically since it has no strong features (except for the hydrogenated form). Ices are present in comets, but they are difficult to detect since they are volatile enough to dissipate when the comet is bright enough to be easily observed in the IR, with present equipment. There are other materials present in comets, but the ones listed above should be the most common and thus dominate the thermal IR spectrum. Most of the IR observations made on comets between 5 and 20 micrometers are summarized. They fall into three broad categories: (1) filter photometry; (2) circular variable filter wheel spectroscopy; and (3) spectra obtained with multidetector grating spectrometers.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 129-133
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  • 84
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    IR-dust observations of Comet Tempel 2 with CRAF VIMS (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Measurement strategies are now being planned for using the Visual and Infrared Mapping Spectrometer (VIMS) to observe the asteroid Hestia, and the nucleus, and the gas and dust in the coma of comet P/Tempel 2 as part of the Comet Rendezvous Asteroid Flyby (CRAF) mission. The spectral range of VIMS will cover wavelengths from 0.35 to 5.2 micrometers, with a spectral resolution of 11 nm from 0.35 to 2.4 micrometers and of 22 nm from 2.4 to 5.2 micrometers. The instantaneous field of view (IFOV) provided by the foreoptics is 0.5 milliradians, and the current design of the instrument provides for a scanning secondary mirror which will scan a swath of length 72 IFOVs. The CRAF high resolution scan platform motion will permit slewing VIMS in a direction perpendicular to the swath. This enables the building of a two dimensional image in any or all wavelength channels. Important measurements of the dust coma will include the onset of early coma activity, the mapping of gas and dust jets and correlations with active nucleus areas, observations of the dust coma from various scattering phase angles, coverage of the low wavelength portion of the thermal radiation, and the 3.4 micrometer hydrocarbon emission. A description of the VIMS instrument is presented.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 136
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  • 85
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    Current status of the international Halley Watch infrared net archive (1988)
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    Publication Date: 2013-08-31
    Description: The primary purposes of the Halley Watch have been to promote Halley observations, coordinate and standardize the observing where useful, and to archive the results in a database readily accessible to cometary scientists. The intention of IHW is to store the observations themselves, along with any information necessary to allow users to understand and use the data, but to exclude interpretations of these data. Each of the archives produced by the IHW will appear in two versions: a printed archive and a digital archive on CD-ROMs. The archive is expected to have a very long lifetime. The IHW has already produced an archive for P/Crommelin. This consists of one printed volume and two 1600 bpi tapes. The Halley archive will contain at least twenty gigabytes of information.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 117-122
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  • 86
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    Focus on the future (1988)
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    Description: An assessment is made of what was learned from Halley and recommendations are made for future directions for infrared studies of comets and supporting lab investigations. The following issues are addressed: (1) What steps can be taken to achieve consistent interpretation of Halley infrared data; (2) How successful has the Halley Watch been for infrared studies; (3) What supporting lab research is needed; (4) What are the key infrared observations needed for future comets; and (5) How do current and future NASA programs relate to comet studies.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 105-116
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  • 87
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    Interstellar grain chemistry and the composition of comets (1988)
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    Publication Date: 2013-08-31
    Description: During the past 15 years considerable progress in observational techniques has been achieved in the middle infrared, the spectral region most diagnostic of molecular vibrations. Spectra of many different astronomical infrared sources are now available. By comparing these astronomical spectra with the spectra of lab ices, one can determine the composition and abundance of the icy materials frozen on the cold dust grains present in the interior of molecular clouds. In the experiments described, the assumption is made that cometary ices are similar to interstellar ices. As an illustration of the processes which can take place as an ice is irradiated and subsequently warmed, the infrared spectra is presented of the mixture H2O:CH3OH:CO:NH3:C6H14 (100:50:10:10:10). Apart from the last species, the ratio of these compounds is representative of the simplest ices found in interstellar clouds.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 127-128
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  • 88
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    Possible identifications of the 3.4 micrometer feature (1988)
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    Publication Date: 2013-08-31
    Description: A feature at 3.4 micrometer was first detected in Comet Halley by the IKS spectrometer on board the Vega 1 probe; and subsequently from the ground. The feature has since been reported in Comet Wilson. The presence of the feature is of considerable interest for a number of reasons. First, it may represent the detection of a new parent molecule, and when combined with data from Giotto and Vega yield new information on cometary chemistry and the early solar system composition. Secondly, it may represent a link to the interstellar medium, the feature corresponds in wavelength and shape with an interstellar feature seen in absorption in a luminous star, towards the Galactic center known as GC-IRS7. The feature in turn is thought to be related with a growing family of unidentified infrared emission features seen in stellar objects, planetary nebulae, reflection nebulae, HII regions and extra galactic sources. These features occur at wavelengths 3.3, 3.4, 3.5, 6.2, 7.7, 8.6, and 11.25 micrometers. Further identification theory is given.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 86-90
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  • 89
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    A two component model for thermal emission from organic grains in Comet Halley (1988)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Observations of Comet Halley in the near infrared reveal a triple-peaked emission feature near 3.4 micrometer, characteristic of C-H stretching in hydrocarbons. A variety of plausible cometary materials exhibit these features, including the organic residue of irradiated candidate cometary ices (such as the residue of irradiated methane ice clathrate, and polycyclic aromatic hydrocarbons. Indeed, any molecule containing -CH3 and -CH2 alkanes will emit at 3.4 micrometer under suitable conditions. Therefore tentative identifications must rest on additional evidence, including a plausible account of the origins of the organic material, a plausible model for the infrared emission of this material, and a demonstration that this conjunction of material and model not only matches the 3 to 4 micrometer spectrum, but also does not yield additional emission features where none is observed. In the case of the residue of irradiated low occupancy methane ice clathrate, it is argued that the lab synthesis of the organic residue well simulates the radiation processing experienced by Comet Halley.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 83-84
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  • 90
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    The spectral properties of interplanetary dust particles (1988)
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    Publication Date: 2013-08-31
    Description: The observed spectral and mineralogical properties of interplanetary dust particles (IDP) allows the conclusion that: (1) the majority of IDP infrared spectra are dominated by olivine, pyroxene, or layer lattice silicate minerals, (2) to the first order the emission spectra of comets Halley and Kohoutek can be matched by mixtures of these IDP infrared types, implying that comets contain mixtures of these different crystalline silicates and may vary from comet to comet and perhaps even within a single comet, (3) do not expect to observe a single 20 micron feature in cometary spectra, (4) carbonaceous materials dominate the visible spectra properties of the IDPs even though the mass in these particles consists primarily of silicates, and (5) the particle characteristics summarized need to be properly accounted for in future cometary emission models.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 68-72
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  • 91
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    PIA update: Correlation analyses of mass spectra (1988)
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    Publication Date: 2013-08-31
    Description: The PIA instrument aboard the Giotto spacecraft (a time of flight spectrometer) has been presented elsewhere. The mass spectra used in this analysis were decoded and mass numbers assigned according to the presence of carbon and silver, using the global values for these elements in their spectral absence. The results presented here were obtained using a frequency of occurrence based on analysis which correlated how often mass numbers appear in the mass spectra and which mass numbers tend to occur together in the same spectra; no amplitude information is utilized. The data are presented as plots of mass vs coincident mass for different subsets of the PIA data set, with both axes having units of atomic mass. Frequency contours are plotted at approximately five percent contour intervals, relative to the maximum AMU occurrence in that plot. The plots presented are symmetrical about the matrix diagonal, i.e., every mass is coincident with itself in a given spectra.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 64-65
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  • 92
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    Grain optical properties (1988)
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    Description: The optical properties of small grains provide the link between the infrared observations presented in Chapter 1 and the dust composition described in Chapter 3. In this session, the optical properties were discussed from the viewpoint of modeling the emission from the dust coma and the scattering in order to draw inference about the dust size distribution and composition. The optical properties are applied to the analysis of the infrared data in several ways, and these different uses should be kept in mind when judging the validity of the methods for applying optical constants to real grains.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 22-49
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  • 93
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    Approaches to non-linear aerodynamic analysis and design (1988)
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    Publication Date: 2013-08-31
    Description: Within the last two decades, there has been increasing emphasis on developing more sophisticated computational fluid dynamics (CFD) methods to handle a wide range of problems of interest to the aerospace community. The comprehensive picture of the status of CFD development and capability as well as an assessment of requirements and future directions are given. An independent review and assessment was also carried out by the author as part of the current assignment and the results are outlined herein.
    Keywords: AERODYNAMICS
    Type: Hampton Inst., NASA/American Society for Engineering Educ; Hampton Inst., NASA(
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  • 94
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    Design of lunar base observatories (1988)
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    Publication Date: 2013-08-31
    Description: Several recently suggested concepts for conducting astronomy from a lunar base are cited. Then, the process and sequence of events that will be required to design an observatory to be emplaced on the Moon are examined.
    Keywords: ASTRONOMY
    Type: NASA, Lyndon B. Johnson Space Center, Future Astronomical Observatories on the Moon; p 127-134
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  • 95
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    Space and lunar-based optical telescopes (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The growth of space observatories, especially at optical wavelengths, during the next several decades is considered. It is concluded that large aperture optical telescopes on the Moon, possibly constructed of lunar glasses, will be very competitive with and in some instances superior to Earth orbiting telescopes.
    Keywords: ASTRONOMY
    Type: NASA, Lyndon B. Johnson Space Center, Future Astronomical Observatories on the Moon; p 63-71
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  • 96
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    Astronomical interferometry on the Moon (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Optical interferometric arrays are particularly attractive candidates for a manned lunar base. A permanent lunar can provide support for a variety of astronomical investigations. An optical interferometric array, perhaps of the general form of the VLA but designed for optical instead of radio wavelengths, would lead to a qualitative advance in the understanding of the universe. A wide variety of scientific problems could be addressed by such an instrument. The stellar analogs of the solar cycle, the behavior of sunspots on other stars, the magnetic field configurations of other stars, and the behavior of dynamic plasma phenomena such as flares and winds are examples of star related problems that ultimately would lead to both increased understanding of our Sun and fundamental knowledge of the manner in which stars form and evolve.
    Keywords: ASTRONOMY
    Type: NASA, Lyndon B. Johnson Space Center, Future Astronomical Observatories on the Moon; p 73-83
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  • 97
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    Overview of lunar-based astronomy (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The opportunities along with the advantages and disadvantages of the Moon for astronomical observatories are carefully and methodically considered. Taking a relatively unbiased approach, it was concluded that lunar observatories will clearly be a major factor in the future of astronomy in the next century. He concludes that ground based work will continue because of its accessibility and that Earth orbital work will remain useful, primarily for convenience of access in constructing and operating very large space systems. Deep space studies will feature not only probes but extensive systems for extremely long baseline studies at wavelengths from gamma rays through visible and IR out to radio is also a conclusion drawn, along with the consideration that lunar astronomy will have found important permanent applications along lines such as are discussed at the present symposium and others quite unsuspected today.
    Keywords: ASTRONOMY
    Type: NASA, Lyndon B. Johnson Space Center, Future Astronomical Observatories on the Moon; p 37-42
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  • 98
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    Cometary dust size distributions from flyby spacecraft (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Pior to the Halley flybys in 1986, the distribution of cometary dust grains with particle size were approximated using models which provided reasonable fits to the dynamics of dust tails, anti-tails, and infrared spectra. These distributions have since been improved using fluence data (i.e., particle fluxes integrated over time along the flyby trajectory) from three spacecraft. The fluence derived distributions are appropriate for comparison with simultaneous infrared photometry (from Earth) because they sample the particles in the same way as the IR data do (along the line of sight) and because they are directly proportional to the concentration distribution in that region of the coma which dominates the IR emission.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 137-138
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  • 99
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    Laboratory investigations (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Laboratory studies related to cometary grains and the nuclei of comets can be broken down into three areas which relate to understanding the spectral properties, the formation mechanisms, and the evolution of grains and nuclei: (1) Spectral studies to be used in the interpretation of cometary spectra; (2) Sample preparation experiments which may shed light on the physical nature and history of cometary grains and nuclei by exploring the effects on grain emissivities resulting from the ways in which the samples are created; and (3) Grain processing experiments which should provide insight on the interaction of cometary grains with the environment in the immediate vicinity of the cometary nucleus as the comet travels from the Oort cloud through perihelion, and perhaps even suggestions regarding the relationship between interstellar grains and cometary matter. A summary is presented with a different view of lab experiments than is found in the literature, concentrating on measurement techniques and sample preparations especially relevant to cometary dust.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 91-104
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  • 100
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    On the carbon abundance in Comet Halley derived from the 3 micron feature: Comparison with interstellar dust (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: In spite of some similarities with the infrared features observed in the interstellar medium, the 3 micron signature observed in comet Halley's spectrum shows two distinct differences: (1) the 3.28 micron and 3.37 micron cometary features are both in emission, while the 3.37 micron interstellar feature is most often observed in absorption; and (2) there is no associated emission feature beyond 6 micron in the cometary spectrum. These two facts can be simply explained if it is assumed that the excitation mechanism is resonance fluorescence by the solar IR radiation field. With this assumption, it is found that hydrocarbons are present in roughly equal quantities in both the saturated forms, with a total carbon abundance of about 30 percent of H2O. This carbon abundance can be compared with the abundances derived for the interstellar dust when all condensed (or condensable) components are considered.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 85
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