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  • 1
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    Radial and latitudinal gradients in the interplanetary magnetic field - Evidence for meridional flux transport (1986)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Magnetic field data obtained by the Pioneer 10 and 11 spacecraft in the heliosphere from 1972-1982 and earth orbiting satellite data are examined in terms of radial and latitudinal gradients in the field components and magnitude. The data reveal that higher than expected gradients are observed in the magnetic field and time variations affect the field throughout the low-latitude heliosphere. It is determined that the high radial gradient is caused by meridional flux transport with low-latitude field lines moving to higher heliographic latitudes. High pressure near the solar equator and pressure due to heating in compressive solar wind interaction regions and the large field magnitudes that occur in these regions are investigated as mechanisms that produce the meridional flux. A solar cycle variation in the level of flux transport is analyzed.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 91; 6760-676
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  • 2
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    Theoretical interpretation of the observed interplanetary magnetic field radial variation in the outer solar system (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observations of the azimuthal component of the IMF are evaluated through the use of an MHD model which shows the effect of magnetic flux tubes opening in the outer solar system. It is demonstrated that the inferred meridional transport of magnetic flux is consistent with predictions by the MHD model. The computed azimuthal and radial magnetic flux deficits are almost identical to the observations. It is suggested that the simplest interpretation of the observations is that meridional flows are created by a direct body force on the plasma. This is consistent with the analytic model of Nerney and Suess (1975), in which such flux deficits in the IMF arise naturally from the meridional gradient in the spiralling field.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 4378-438
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  • 3
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    Asteroids: A source of natural resources for terrestrial and extra-terrestrial applications (1976)
    In:  CASI
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    Publication Date: 2016-06-07
    Keywords: ASTROPHYSICS
    Type: Lunar Science Inst., Abstracts of Papers Presented at a Special Session of the Seventh Annual Lunar Science Conference on Utilization of Lunar Materials and Expertise for Large Scale Operations in Space; p 143-147
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  • 4
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    The Parker spiral configuration of the interplanetary magnetic field between 1 and 8.5 AU (1980)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The magnetic field data from the Pioneer 10 and 11 spacecraft show that the field directions between 1 and 8.5 AU are in accordance with the Parker spiral directions within quiet and interaction regions. The included angle between the inward and outward sectored field directions is near 180 deg; the field direction manifests greater variability in quiet regions than in interaction zones. The fractional polarities below 10 deg heliographic latitude are dominated by temporal variations; however, dual-spacecraft investigations permitted a significant latitudinal gradient to be extracted. The sector structure extended occasionally to 16 deg heliographic latitude during the period of average current sheet inclination in 1976; it is proposed that the fast streams associated with interaction regions may move the current sheet to higher latitudes when the source of the fast plasma is in the southern solar hemisphere.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 85; Dec. 1
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  • 5
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    An interactive companion to the S star HD 35155 (1991)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Low-dispersion UV spectra taken by the IUE satellite of an S star HD 35155 are presented. It is shown that the spectra contain strong emission lines of multiply ionizes species and an excess continuous emission shortward of 2000 A. Because neither the photospheres nor chromospheres of S stars are expected to produce multiply ionized ions, the emission lines and the excess short-wave emission seen in the HD 35155 spectra are interpreted as an evidence of the presence of a hot nearby compact companion. Some inferences regarding the compact companion and the possible location of the source of the emission lines of multiply ionized ions are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 383; 842-852
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  • 6
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    Geometry and pulse profiles of x-ray pulsars: Asymmetric relativistic fits to 4U1538 - 52 and vela x-1 (1995)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: Model calculation of inhomogenuous magnetized neutron star atmospheres are used to analyze the phase-dependent spectra of 4U 1538-52 and Vela X-1 taking into account general relativistic effects. A chi (exp 2) fitting procedure is used on the Ginga data for these objects to determine the geometry and the magnetic structure of the polar caps, as well as their size and location on the surface of the stars. Other parameters determined by the fit are the masses and radii of neutron stars, the accretion rates, and the rotation and magnetic inclination angles including an azimuthal offset to reproduce the asymmetry of the pulse shapes. We find that general relativistic effects play a significant role in determining the derived cap sizes, the fluxes, and the observational appearance of the pulses. There is evidence that the polar caps are unequal and nonantipodal, suggesting either an off-center or bent magnetic axis, or a strong nondipole component. The magnetic field structure is approximated by a two-component model. The rotation axes are inferred to be moderately close to the mean magnetic axes and seen at large inclinations with respect to the line of sight.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 444; 1; p. 405-414
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  • 7
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    Ultraviolet and optical studies of binaries with luminous cool primaries and hot companions. IV - Further IUE detections (1993)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: We have obtained IUE spectra for 31 middle and late-type giant and supergiant stars whose TD-1 fluxes or ground-based spectra indicate the presence of a hot component, or whose radial velocities indicate an unseen component. Stellar components earlier than type F1 were detected in 22 cases. While 20 of the hot secondaries are seen weakly in optical spectra, two are UV discoveries: HD 58134 and HD 183864. The hot companions are classified accurately by temperature class from their far-UV spectra. The interstellar extinction of each system and the relative luminosities of the components are derived from the UV and optical fluxes, using a new grid of UV intrinsic colors for hot dwarfs. We find that many giant stars apparently have companions which are too hot and hence too luminous for consistency with the primary's spectral classification.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 412; 2; p. 814-826.
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  • 8
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    Companions to bright S and MS stars - Technetium deficiency and binarity (1993)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: To test the popular hypothesis that technetium-deficient stars of spectral types S and MS are mass-transfer binaries, we have searched for ultraviolet light from the putative hot secondaries in spectra taken with the SWP spectrograph of IUE. Although most S and MS stars are apparently thermally pulsing AGB (asymptotic giant branch) stars whose surfaces have been enriched with s-process elements and carbon dredged up from the interior, those stars whose spectra show enhanced s-process elements but no Tc are widely believed to be cooler analogs of the Ba II stars, which apparently owe their unusual abundances to prior mass transfer, the Tc from which has decayed away. We report IUE observations of 15 S and MS stars with the SWP, including the identification of six hot companions. Assembling all the IUE observations made to date, we find clear support for the mass-transfer hypothesis, confirming evidence from other lines of research. We further discuss the ages of the companions and the implications of these discoveries for stellar evolution.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 402; 2; p. 667-679.
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  • 9
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    First results from the Goddard High-Resolution Spectrograph - The chromosphere of Alpha Tauri (1991)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: The K5 III star Alpha Tau was observed with the Goddard High Resolution Spectrograph on November 27, 1990 as part of the Science Assessment Program for the HST. The spectra show intersystem and permitted chromospheric emission lines of semiforbidden C II and Si II, Fe II, Fe I, Ni II, and Co II. Resolved profiles of the semiforbidden C II lines indicate a complex chromospheric turbulent velocity distribution with mean value of roughly 24 km/s, while their observed wavelengths indicate a 4 km/s downflow of the semiforbidden C II plasma. Twenty-five new emission lines have been found in the 2320-2370 A region, 17 of which have been identified with the aid of Skylab data obtained above the solar limb, including four lines from Co II (UV 8) and an Fe I (UV 12) line.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 377; L45-L48
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  • 10
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    A white dwarf companion to the main-sequence star 4 Omicron(1) Orionis and the binary hypothesis for the origin of peculiar red giants (1988)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Ultraviolet spectra of the peculiar red giants (PRGs) called MS stars are investigated, and the discovery of a white dwarf (WD) companion to the MS star 4 Omicron(1) Orionis is reported. The observations and data analysis are discussed and compared with those for field WDs in order to derive parameters for the WD and the luminosity of the primary. Detection limits for the other MS stars investigated are derived, and the binary hypothesis for PRGs is reviewed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 327; 214-221
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