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  • 1
    Publication Date: 2014-09-18
    Description: Starburst galaxies are defined in several ways (colors, optical spectroscopic signatures, and excess radio flux), and observational evidence indicating that episodes of rapid star formation occur in many galaxies with active nuclei is presented. There is a good correlation of 100 micron luminosity with CO emission, and of both quantities with excess nonthermal radio flux. This fact requires some linkage between central and global star formation rates. In addition, the presence of starbusts distorts the appearance of the molecular gas in which they occur. Using far infrared color temperatures and comparisons of CO isotopes, it is shown that the strong (12)CO emission in these galaxies does not accurately trace the H2 distribution, probably because the starburst raises the avearage temperature of the cloud ensemble.
    Keywords: SPACE RADIATION
    Type: NASA. Ames Research Center Airborne Astron. Symp.; p 287-291
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  • 2
    Publication Date: 2019-06-28
    Description: A modeling analysis is carried out of six experimental phase space density profiles for nearly equatorially mirroring protons using methods based on the approach of Thomsen et al. (1977). The form of the time-averaged radial diffusion coefficient D(L) that gives an optimal fit to the experimental profiles is determined under the assumption that simple satellite plus Ring E absorption of inwardly diffusing particles and steady-state radial diffusion are the dominant physical processes affecting the proton data in the L range that is modeled. An extension of the single-satellite model employed by Thomsen et al. to a model that includes multisatellite and ring absorption is described, and the procedures adopted for estimating characteristic satellite and ring absorption times are defined. The results obtained in applying three representative solid-body absorption models to evaluate D(L) in the range where L is between 4 and 16 are reported, and a study is made of the sensitivity of the preferred amplitude and L dependence for D(L) to the assumed model parameters. The inferred form of D(L) is then compared with that which would be predicted if various proposed physical mechanisms for driving magnetospheric radial diffusion are operative at Saturn.
    Keywords: SPACE RADIATION
    Type: Journal of Geophysical Research; 88; Feb. 1
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  • 3
    Publication Date: 2019-06-28
    Description: A balloon-borne superconducting magnet spectrometer was used to measure the absolute flux of cosmic-ray electrons. The instrument consisted of a gas Cerenkov detector, a momentum spectrometer, and a lead-scintillator shower counter. In order to determine electron flux in the interstellar medium, observed fluxes for energy loss in the atmosphere and the payload were corrected, taking into account solar modulation effects and bremsstrahlung energy losses. Fluxes were measured at an average atmospheric depth of 5.8 g/sq cm, and the solar modulation was 300 MeV. A cosmic-ray electron flux of 367 E to the exp(3.15 + or -0.2) per sq m/sr s GeV was obtained in the energy range 4.5-63.5 GeV. The uncertainty of the absolute (electron-positron) flux was 10 percent. A summary of the electron data is given in a table.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 622-632
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  • 4
    Publication Date: 2019-06-28
    Description: An H I detection survey of eleven elliptical galaxies with powerful nuclear radio sources was conducted, using the 305 m antenna of Arecibo Observatory, to test the hypothesis that large H I mass is conductive to the formation of nuclear radio sources in elliptical galaxies. The H I was detected in emission in UGC 09114 and was possibly detected in absorption in UGC 06671. Observations of the remaining galaxies were not sensitive enough to support or refute the hypothesis. Data was combined from other H I surveys and spectroscopic surveys to search for correlations of H I mass with other galactic properties and environmental conditions. Strong correlations of (O II) lambda 3727 emission with H I content and with nuclear radio power were found. The latter two properties may simply indicate, respectively, whether a significant amount of gas is available to be ionized and whether energy is provided by nuclear activity for ionization. No dependence of H I content on optical luminosity or on degree of isolation from other galaxies was found.
    Keywords: SPACE RADIATION
    Type: NASA-TM-83870 , NAS 1.15:83870
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  • 5
    Publication Date: 2019-06-28
    Description: Balloon-borne measurements of the atmospheric and diffuse gamma-ray flux in the energy range 0.4-7.0 MeV with a Compton telescope, which included pulse-shape discrimination of the first scattering detector and a time-of-flight system between the first and second detector elements, are reported. Comparison of the diffuse cosmic gamma-ray flux to the atmospheric gamma rays indicates that 0.2-5.0 MeV is the optimum energy range for measurements made at the top of the earth's atmosphere. The measured total atmospheric gamma-ray flux between zero and 40 deg has an energy spectrum that agrees with the calculations of Ling (1975). Observations indicate that the ratio of the diffuse to atmospheric gamma ray fluxes at 3.5 g/sq cm is a maximum, about 1.0, between 0.7 and 3.0 MeV.
    Keywords: SPACE RADIATION
    Type: Astrophysical Journal; vol. 248
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  • 6
    Publication Date: 2019-07-13
    Description: The gamma-ray spectrometer on SMM is sensitive to bursts within its field of view with intensities greater than 0.000005 erg/sq cm above 100 keV. It has detected 17 events between February 1980 and March 1981 with the characteristics of cosmic gamma-ray bursts. The most intense burst, on 19 April 1980, had a photon spectrum consistent with a power law with spectral index - 2.5 from 300 keV to approximately 7 MeV. It is not possible at present to exclude the sun as the source of this burst. Spectra of 11 of the bursts have been studied for line features with no clear evidence for line emission greater than 300 keV. The continuum radiation from about half of these events have hard emission extending to approximately equal to or greater than 2 MeV.
    Keywords: SPACE RADIATION
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 7
    Publication Date: 2019-07-13
    Keywords: SPACE RADIATION
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 8
    Publication Date: 2019-07-13
    Description: A gamma ray burst was detected on March 25, 1978 by the High Energy X-ray and Low Energy Gamma Ray Experiment on HEAO-1. The burst spectrum shows an absorption feature at 55 + or - 5 keV with an equivalent width of 13 + or - 3 keV, values commensurate with those of similar features observed by the KONUS experiment. The burst spectrum also is characterized by a hard component extending from about 0.25-6 MeV. This component can be interpreted in terms of a fireball model for gamma ray bursts, which places the distance to the source at 1 kpc. The integrated fluence of the burst between 0.025 and 6 MeV is 1.5 x 10 to the -5th ergs/sq cm. The burst source has been localized to within a degree of RA = 237.5 deg and Dec = 76.2 deg.
    Keywords: SPACE RADIATION
    Type: International Cosmic Ray Conference; Aug 22, 1983 - Sep 03, 1983; Bangalore; India
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  • 9
    Publication Date: 2006-02-14
    Description: The objective of this experiment is to measure the flux and energy spectrum of protons with energies of 1 to MeV. These protons are trapped on the Earth's magnetic field lines as part of the inner radiation belt, or Van Allen zone. The proton will be encountered predominantly in the South Atlantic anomaly at a 90 deg pitch angle.
    Keywords: SPACE RADIATION
    Type: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 109-112
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  • 10
    Publication Date: 2011-08-18
    Description: Searches were made for pulsed high energy (E greater than 35 MeV) gamma radiation from 43 pulsars using the SAS-2 data base and radio parameters. No positive results were found, and the upper limits are consistent with the concept that gamma ray production efficiency increases with increasing apparent age. Two limits suggest that efficiency cannot be a simple function of apparent age beyond 1,000,000 years. Previously announced in STAR as N83-24463
    Keywords: SPACE RADIATION
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 127; 1, Oc
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