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  • 11
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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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  • 12
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    Observations of diffuse interstellar lines toward stars with low column densities of H2 (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The diffuse interstellar band at 5780 A has been observed in lines of sight where the column density of H2 is less than 10 to the 16th/sq cm. The strength of 5780 A toward Gamma Cas, Kappa Ori, and Rho Leo argues strongly against a molecular carrier of the 5780 A feature. The interstellar band at 5797 A also appears to be present in Kappa Ori and Rho Leo. Although the exact mechanism remains unclear, it is concluded that the diffuse features at 5780 A and 5797 A are carried by dust grains.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 266
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  • 13
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    Solar flare shocks in interplanetary space and solar flare particle events (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Data on particle events resulting from three solar flares are examined to determine the effect of shocks on the population of protons at energies not less than 30 MeV. The arrival of the shock is found to mark the start of the decay phase of the particle event, and changes in particle anisotropy are found to be related to features in the shock structure. Two distinct modes of particle propagation are found to exist: a direct component, and a second component which has a time scale of days and is seen in two of the flares which also produced interplanetary shock. In addition, a model is described in which the protons are accelerated by the shocks, and it is shown to be in agreement with observations.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 87; Feb. 1
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  • 14
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    Ultraviolet interstellar extinction toward 1367 stars observed by ANS (1981)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Five-band UV photometry is used to investigate the character of interstellar extinction toward 1367 stars of spectral type B3 and earlier, with observations producing a galactic average of 5.11, 4.78, 6.52, 4.10 and 1.95 at 1550, 1800, 2200, 2500, and 3300 A, respectively. Differences in the strengths of the UV extinction features of these stars appear to be independent, since objects with either strong or weak 2200 A extinction can have strong, normal or weak far-UV extinction. Further investigation reveals that some of the deviant stars are embedded in localized regions whose average extinction curves diverge dramatically from the galactic mean. The anomalous extinction of these regions attests to localized inhomogeneities in the UV characteristics of interstellar dust. Because the evaluation of UV extinction toward a particular star would be more accurate if based on the average curve of the region immediately surrounding that star rather than that of the entire Galaxy, it is recommended that the galactic average presented be used with caution to correct astronomical data of individual objects.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 248
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  • 15
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    A measurement of the medium-scale anisotropy in the cosmic microwave background radiation (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Observations from the first flight of the Medium Scale Anisotropy Measurement (MSAM) are analyzed to place limits on Gaussian fluctuations in the cosmic microwave background radiation (CMBR). This instrument chops a 30 min beam in a three-position pattern with a throw of +/- 40 min; the resulting data is analyzed in statistically independent single- and double-difference sets. We observe in four spectral channels at 5.6, 9.0, 16.5, and 22.5/cm, allowing the separation of interstellar dust emission from CMBR fluctuations. The dust component is correlated with the IRAS 100 micron map. The CMBR component has two regions where the signature of an unresolved source is seen. Rejecting these two source regions, we obtain a detection of fluctuations which match CMBR in our spectral bands of 0.6 x 10(exp -5) is less than Delta (T)/T is less than 2.2 x 10(exp -5) (90% CL interval) for total rms Gaussian fluctuations with correlation angle 0.5 deg, using the single-difference demodulation. Fore the double difference demodulation, the result is 1.1 x 10(exp -5) is less than Delta(T)/T is less than 3.1 x 10(exp -5) (90% CL interval) at a correlation angle of 0.3 deg.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 422; 2; p. L37-L40
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  • 16
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    A critical analysis of interstellar Zn and Cr as galactic abundance benchmarks for quasar absorbers (1995)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present interstellar gas-phase abundances of zinc and chromium in the Milky Way for comparison with the abundances of these elements in damped Ly-alpha systems at redshifts near z approximately 2. We make use of both IUE (International Ultraviolet Explorer) and GHRS (Goddard High Resolution Spectrograph) archival information in deriving the Milky Way values and find that the average difference in (Zn/H) and (Cr/Zn) between the Milky Way and damped Ly-alpha systems at large N(H1) is about 0.9 dex. The Zn/H values we find for the Milky Way are approximately -0.2 to -0.7 dex below solar and are due in large part to depletion of Zn onto dust grains. The amount of this gas-phase depletion is variable and depends upon the H1 column density and molecular fraction of the gas. Milky Way sight lines having low molecular fractions have values of (Zn/H) within approximately 0.2 dex of the solar value. Combined with larger values of (Cr/Zn) found for the damped Ly-alpha systems, this result confirms that measures of (Zn/H) should accurately reflect the lower gas-phase abundances of Zn found in these systems.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 445; 1; p. L27-L30
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  • 17
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    Analysis of Skylab/Apollo Telescope Mount S-056 observations based on a force-free magnetic field model (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: Data obtained from the S-056 X-ray experiment on Skylab/ATM have been analyzed based on the assumption that the magnetic fields in the chromosphere and lower corona are force-free. Underlying the analysis is the hypothesis that the observed X-ray filaments coincide with magnetic field lines. The photographic recording of the filaments can then be compared with the projection along the line of sight of the computed magnetic field lines of the model. Ground-based observations of the longitudinal magnetic field component complement the X-ray data and are used in the theoretical interpretation.
    Keywords: ASTROPHYSICS
    Type: AIAA PAPER 74-1235
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  • 18
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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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  • 19
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    IRAS observations of young stellar objects in the Corona Australis dark cloud (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The young stellar object (YSO) population associated with the dark cloud complex in Corona Australis is studied by synthesizing IRAS data with newly obtained near-IR and mid-IR photometry and previously published optical/IR data. Twenty-four YSOs in the Cr A complex are identified. The observed range of spectral energy distribution shapes and bolometric luminosities are consistent with those observed in other dark clouds. The duration and efficiency of star formation are found to be similar to the Rho Ophiuchi IR cluster. The low number of YSOs compared to other dark clouds is understood by a reevaluation of the molecular mass of the R Cr A cloud which shows it to be much less massive than previously assumed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 397; 2; p. 520-533.
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  • 20
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    The amplitude and spectral index of the large angular scale anisotropy in the cosmic microwave background radiation (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: In many cosmological models, the large angular scale anisotropy in the cosmic microwave background is parameterized by a spectral index, n, and a quadrupolar amplitude, Q. For a Harrison-Peebles-Zel'dovich spectrum, n = 1. Using data from the Far Infrared Survey (FIRS) and a new statistical measure, a contour plot of the likelihood for cosmological models for which -1 less than n less than 3 and 0 equal to or less than Q equal to or less than 50 micro K is obtained. Depending upon the details of the analysis, the maximum likelihood occurs at n between 0.8 and 1.4 and Q between 18 and 21 micro K. Regardless of Q, the likelihood is always less than half its maximum for n less than -0.4 and for n greater than 2.2, as it is for Q less than 8 micro K and Q greater than 44 micro K.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 432; 1; p. L15-L18
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