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  • 1
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    The 1985 May superoutburst of the dwarf nova OY Carinae. II - IUE and Exosat observations (1988)
    In:  Other Sources
    Details
    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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  • 2
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    Infrared photometry of Comet P/Halley pre- and post-perihelion (1988)
    In:  Other Sources
    Details
    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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  • 3
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    IR-dust observations of Comet Tempel 2 with CRAF VIMS (1988)
    In:  CASI
    Details
    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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  • 4
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    High-spectral resolution observations of the 3.29 micron emission feature: Comparison to QCC and PAHs (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Two of the most promising explanations for the origin of the interstellar emission features observed at 3.29, 3.4, 6.2, 7.7, 8.6, and 11.3 microns are: quenched carbonaceous composite (QCC) and polycyclic aromatic hydrocarbons (PAHs). High resolution spectra are given of the 3.29 micron emission feature which were taken with the Cooled Grating Array Spectrometer at the NASA Infrared Telescope Facility and previously published. These spectra show that the peak wavelength of the 3.29 micron feature is located at 3.295 + or - 0.005 micron and that it is coincident with the peak absorbance of QCC. The peak wavelength of the 3.29 micron feature appears to be the same in all of the sources observed thus far. However, the width of the feature in HD 44179 and Elias 1 is only 0.023 micron, which is smaller than the 0.043 micron width in NGC 7027, IRAS 21282+5050, the Orion nebula, and BD+30 deg 3639. Spectra of NGC 7027, QCC, and PAHs is shown. QCC matches the 3.29 micron interstellar emission feature very closely in the wavelength of the peak, and it produces a single feature. On the other hand, PAHs rarely match the peak of the interstellar emission feature, and characteristically produce multiple features.
    Keywords: ASTRONOMY
    Type: NASA, Ames Research Center, Interstellar Dust: Contributed Papers; p 115-118
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  • 5
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    IUE observations of the dwarf novae OY Car in superoutburst (1986)
    In:  Other Sources
    Details
    Publication Date: 2013-08-29
    Description: The May 1985 superoutburst of OY Car, an eclipsing member of the SU UMa subclass of dwarf novae, was observed extensively with IUE to obtain phase-resolved spectra throughout several orbital cycles, when the superhump was well developed and lay close in phase to the eclipse. The UV lines and continuum vary with orbital phase and show a strong UV eclipse coincident with the optical eclipse. This implies that the superhump source at eclipse is not a strong contributor in the ultraviolet. The UV emission line spectrum and lack of X-ray eclipse suggest the presence of an extended coronal region. The flux evolution observed is unusual in that gross changes occur during the decline from superoutburst. The later spectra actually appear hotter than spectra earlier in the decline, and suggest that, early on, the inner disk is obscured from view.
    Keywords: ASTRONOMY
    Type: ESA Proceedings of an International Symposium on New Insights in Astrophysics. Eight Years of UV Astronomy with IUE; p 467-470
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  • 6
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    IUE survey of planetary nebulae in the large and small magellanic clouds (1986)
    In:  Other Sources
    Details
    Publication Date: 2013-08-29
    Description: Twelve planetary nebulae of the 15 surveyed by IUE in the Megellanic Clouds were analyzed. Chemical abundances and other nebular parameters were determined, along with masses for the central stars. The latter are clustered in the range 0.58 to 0.71 solar masses, contrary to preliminary finding for 3 of the stars. This difference is attributed to the adoption of stellar atmosphere models that better represent the emergent flux distributions below the Lyman limit.
    Keywords: ASTRONOMY
    Type: ESA Proceedings of an International Symposium on New Insights in Astrophysics. Eight Years of UV Astronomy with IUE; p 295-298
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  • 7
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    Does SN 1987A contain a rapidly vibrating neutron star (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: If the recently reported 0.5 ms-period pulsed optical signal from the direction of Supernova 1987A originated in a young neutron star, its interpretation as a rotational period has difficulties. The surface magnetic field would have to be much lower than expected, and the high rotation rate may rule out preferred nuclear equations of state. It is pointed out here that a remnant radial vibration of a neutron star, excited in the supernova event, may survive for several years with about the observed (gravitationally redshifted) period. Heavy ions at the low-density stellar surface, periodically shocked by the vibration, may efficiently produce narrow pulses of optical cyclotron radiation in a surface field of about a trillion gauss.
    Keywords: ASTRONOMY
    Type: CAL-371 , Physics of Systems Containing Neutron Stars; 6 p
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  • 8
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    Monte Carlo simulation of a new gamma ray telescope (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A new Monte Carlo code has been written to simulate the response of the new University of California double scatter gamma ray telescope. This package of modular software routines, written in VAX FORTRAN 77 simulates the detection of 0.1 to 35 MeV gamma rays. The new telescope is flown from high altitude balloons to measure medium energy gamma radiation from astronomical sources. This paper presents (1) the basic physics methods in the code, and (2) the predicted response functions of the telescope. Gamma ray processes include Compton scattering, pair production and photoelectric absorption in plastic scintillator, NaI(Tl) and aluminum. Electron transport processes include ionization energy loss, multiple scattering, production of bremsstrahlung photons and positron annihilation.
    Keywords: ASTRONOMY
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); NS-32; 124-128
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  • 9
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    Multifrequency observations of the superluminal quasar 3C 345 (1986)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Attention is given to the continuum properties of the superluminal quasar 3C 345, on the basis of radio, optical, IR, and X-ray frequency monitorings, as well as by means of simultaneous multifrequency spectra extending from the radio through the X-ray bands. Radio outbursts, which appear to follow IR-optical outbursts by about one year, first occur at the highest frequencies, as expected from optical depth effects; the peak flux is nevertheless often reached at several frequencies at once. The beginning of outbursts, as defined by mm-measurements, corresponds to the appearance of the three known 'superluminal' components. An increase in the X-ray flux during 1979-1980 corresponds to increased radio flux, while the IR flux changes in the opposite sense.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 301; 708-726
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  • 10
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    3 micron spectroscopy of comet Halley (1982i) (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Near-infrared spectroscopy and photometry was obtained of comet Halley in December 1985 when its heliocentric distance was 1.19 AU. No water ice absorption or molecular band emission were observed. The interstellar 3.3-micron emission band was also not observed. The 3-micron spectrum of comet Halley consisted of scattered sunlight at wavelengths less than 3.1 microns and of thermal emission by dust at longer wavelengths.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 310; L45-L48
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