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  • 1
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    Regularly pulsed neutrinos from supernova SN1987A? (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Some consequences of the 8.9 millisecond periodicity observed in neutrino events from SN1987A with the Kamiokonde and IMB experiments are discussed. Interpreting the apparent period as a rotation of a compact object would imply that the neutrino emission is anisotropic and that the neutrino mass, averaged over all observed flavors, is less than 0.2 eV/c-squared. It is also noted that P = 8.9 ms is a reasonable period for very young pulsars.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 328; 503
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  • 2
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    Plasma diagnosis from thermal noise and limits on dust flux or mass in comet Giacobini-Zinner (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Thermal noise spectroscopy was used to measure the density and temperature of the main (cold) electron plasma population during two hours around the point of closest approach of the International Cometary Explorer (ICE) to comet Giacobini-Zinner. The time resolution was 18 seconds in the plasma tail and 54 seconds elsewhere. Near the tail axis, the maximum plasma density was 670/cu cm and the temperature slightly above one volt. Away from the axis, the plasma density dropped to 100/cu cm over 2000 km, then decreased to 10/cu cm over 15,000 km; at the plasma tail, the density fluctuated between 10 and 30/cu cm, and the temperature, between 100,000 and 400,000 K. No evidence was found of grain impact on the spacecraft or antennas in the plasma tail. This yields an upper limit for the dust flux or particle mass, indicating either fluxes or masses in the tail smaller than those implied by models or an anomalous grain structure. Outside the tail, and particularly near 100,000 km from its axis, impulsive noises indicating plasma turbulence were observed.
    Keywords: ASTROPHYSICS
    Type: Science (ISSN 0036-8075); 232; 370-374
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  • 3
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    The C-12/C-13 isotope ratio toward Zeta Ophiuchi (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Observations of interstellar CH(+) toward Zeta Oph were performed to determine the C-12/C-13 isotope ratio in this diffuse cloud. The very high signal-to-noise ratio spectra yield 6 sigma detections of the (C-13)H(+) features at 4232 A and 3957 A; a weighted mean C-12/C-13 ratio of 43 + or - 6 (1 sigma) is obtained. The uncertainty includes the contribution of continuum placement errors, statistical channel-to-channel signal fluctuations, and the error introduced in deconvolving the blended isotopic lines at 4232 A. This result indicates a decrease in the local galactic C-12/C-13 ratio by a factor of 2 during the 4.6 billion yr since the formation of the sun.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 294; L131-L13
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  • 4
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    An optical measurement of the population inversion of the ground state Lambda doublet of interstellar CH (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 294; 238-241
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  • 5
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    A precise measurement of the cosmic microwave background temperature from optical observations of interstellar CN (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Very precise observations (with S/N greater than 2000) of the 3874-angstrom band of interstellar CN toward zeta Per and omicron Per are presented. In the zeta Oph, zeta Per, and omicron Per lines of sight, the saturation-corrected CN line strengths yield respective excitation temperatures of 2.72 plus or minus 0.05 K, 2.76 plus or minus 0.05 K, and 2.78 plus or minus 0.07 K for the J = 0-1 rotational transition at 2.64 mm. By confirming the blackbody character of the cosmic microwave background spectrum at wavelengths near the peak of its flux, the simplest explanation of the background as primeval fireball radiation from a hot bang is reinforced.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 297; 119-132
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  • 6
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    Comet P/Giacobini-Zinner electron and H2O column densities from ICE and ground-based observations (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An H2O(+) emission profile extracted from an optical CCD spectrogram obtained during the ICE/Giacobini-Zinner encounter is compared to the electron density profile deduced from in-situ measurements by the ratio experiment aboard ICE. It is concluded that the electrons and the H2O(+) ions are distributed similarly 9600 km tailward from the cometary nucleus; that the ratio of number densities of H2O(+) ions to electrons is 1/4 at this point; and that the width of the plasma sheet is 16,000 km.
    Keywords: ASTROPHYSICS
    Type: ESA Proceedings of the 20th ESLAB Symposium on the Exploration of Halley's Comet. Volume 1: Plasma and Gas; p 511-514
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  • 7
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    Composition of cosmic-ray nuclei from boron to nickel for 1200 to 2400 MeV per nucleon (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Balloon-borne measurements of cosmic-ray nuclear abundances for Z = 5-28 and energies 1.2-1.4 GeV/nucleon, obtained using the scintillation/Cerenkov-counter telescope and multiwire proportional counter described by Dwyer et al. (1984) on four flights from Texas and Oklahoma during 1973-1975, are reported. The data are presented in tables and graphs and compared with published observations. Charge separation (sigma = 0.2 units for Fe) and exposure factor (38 sq m sr h) are attained, and the findings are found to be in good agreement with the predictions of a simple leaky-box model of the Galaxy and a pure exponential path-length distribution, although a nested-leaky-box model with some truncation is possible. The delay between e-process nucleosynthesis and cosmic-ray acceleration is estimated on the basis of the Co abundance at greater than 100 d and probably greater than 100,000 yr.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 294; 441-454
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  • 8
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    Element abundances at high redshift (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Abundances of Si(+), S(+), Cr(+), Mn(+), Fe(_), and Zn(+) are considered for two absorption-line systems in the spectrum of the QSO PKS 0528 - 250. Zinc and sulfur are underabundant, relative to H, by a factor of 10 compared to their solar and Galactic interstellar abundances. The silicon-, chromium-, iron-, and nickel-to-hydrogen ratios are less than the solar values and comparable to the local interstellar ratios. A straightforward interpretation is that nucleosynthesis in these high-redshift systems has led to only about one-tenth as much heavy production as in the gas clouds around the sun, and that the amount of the observed underabundances attributable to grain depletion is small. The dust-to-gas ratio in these clouds is less than 8 percent of the Galactic value.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 343; L37-L40
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  • 9
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    Observations of neutral atoms in the Rho Ophiuchi cloud (1986)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: New observations of lines from neutral atoms in the lines of sight to three stars in the Rho Oph cloud are combined with literature data to look for evidence of density-enhanced regions with higher elemental depletions than those characterizing the cloud as a whole. The depletions inferred from neutral species, however, are comparable to those measured directly from observations of ions, suggesting that no strong density enhancements exist in the observed lines of sight. This conclusion is supported by electron densities derived from the observed ionization fractions, which also show no evidence for a strong variation of density with depth in the cloud. It appears that the overall density (and overall level of depletion) in the cloud is higher than in typical diffuse clouds, despite the apparent lack of strong condensations with enhanced relative depletions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 303; 433-438
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  • 10
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    Comet P/Giacobini-Zinner electron and H2O(+) column densities from ICE and ground-based observations (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: An H2O(+) spatial mission profile, extracted from an optical CCD spectrogram obtained during the ICE/Giacobini-Zinner encounter, is compared to the electron-density profile that was deduced from in situ measurements by the radio experiment aboard ICE. The electron column density along a line of sight has two components, one from the spherically symmetric coma, and the second from a thin plasma sheet, whenever it is along the line of sight. The deduced electron column-density profile agrees well with the observed H2O(+) emission profile. It is concluded that the electrons and the H2O(+) ions are distributed similarly 9600 km tailward from the cometary nucleus, that the ratio of number densities of H2O(+) ions to electrons is about 1/4 at this point, and that the width of the plasma sheet is about 16,000 km.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal (ISSN 0004-6256); 93; 474-478
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