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  • 1
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    Can Malin's gravitational-field equations be modified to obtain a viable theory of gravity (1976)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Malin's (1975) gravitational theory, which was recently shown by Lindblom and Nester (1975) to be incorrect, is modified by means of a recently proposed method for obtaining viable gravitational theories. The resulting self-consistent theory, which is in effect a Rastall-type modification of the Einstein theory, exhibits nonconservation of momentum, yet agrees with all experimental limits known to date within the post-Newtonian approximation framework.
    Keywords: ASTROPHYSICS
    Type: Nuovo Cimento; vol. 35B
    Format: text
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  • 2
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    Scalar-tensor theory of gravitation with negative coupling constant (1976)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The possibility of a Brans-Dicke scalar-tensor gravitation theory with a negative coupling constant is considered. The admissibility of a negative-coupling theory is investigated, and a simplified cosmological solution is obtained which allows a negative derivative of the gravitation constant. It is concluded that a Brans-Dicke theory with a negative coupling constant can be a viable alternative to general relativity and that a large negative value for the coupling constant seems to bring the original scalar-tensor theory into close agreement with perihelion-precession results in view of recent observations of small solar oblateness.
    Keywords: ASTROPHYSICS
    Type: Nuovo Cimento; vol. 35
    Format: text
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  • 3
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    Scientific possibilities of a solar electric powered rendezvous with comet Encke (1976)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The minimum scientific spacecraft instrumentation is considered that is likely to result in as complete an understanding of the composition, structure, and activity of a cometary nucleus as is possible without landing on it. The payload will also give useful results on secondary goals of a better understanding of physical processes in the inner and outer coma. Studies of composition, by means of an actual landing on the surface, details of the internal structure of the nucleus, and sample return were considered beyond the scope of this mission.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Study of Comets, Part 2; p 1071-1083
    Format: application/pdf
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  • 4
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    Science aspects of 1980 ballistic missions to comet Encke, using Mariner and Pioneer spacecraft (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Science aspects of a 1980 spacecraft reconnaissance of Comet Encke are considered. The mission discussed is a ballistic flyby (more exactly, a fly-through) of P/Encke, using either a spin stabilized spacecraft, without despin of instruments, or a 3-axis stabilized spacecraft.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Study of Comets, Part 2; p 1058-1070
    Format: application/pdf
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  • 5
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    CO observations of the expanding envelope of IRC + 10216 (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The paper reports high-sensitivity observations of (C-12)O and (C-13)O in the infrared source IRC + 10216, which were made with the NRAO 11-m telescope at frequencies of 115.2712 and 110.2014 GHz, respectively. The emission-line profiles are found to be in good qualitative agreement with model profiles predicted for a spherically symmetric and uniformly expanding envelope. Analysis of the profile shapes indicates that the (C-12)O line is optically thick, while the (C-13)O line is both optically thin and double-peaked. It is shown that the shape of the (C-12)O line is determined largely by the motion of the gas and that the expansion velocity at the edges of the CO cloud is 15 km/s, in contrast to 12 km/s for more centrally confined molecules. Based on the estimated (C-13)O content, the envelope mass is estimated to be 0.5 solar mass.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 204; Mar. 1
    Format: text
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  • 6
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    The C-12/C-13 ratio in stellar atmospheres. VI - Five luminous cool stars (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A simple curve-of-growth technique is described for extracting the C-12/C-13 ratio for M stars from high-resolution spectra of CO infrared vibration-rotation lines. The technique is applied to the CO lines at 1.6 and 2.3 microns in spectra of two M supergiants (Alpha Ori and Alpha Sco), two M giants (Alpha Her and Beta Peg), and a Mira-type variable (Chi Cyg). As a check on the CO analysis, the C-12/C-13 ratio is derived from the red CN system at 8000 A for Alpha Sco, Alpha Ori, and Beta Peg. The CO analysis is also applied to the K giant Alpha Boo as a check. The CN and CO results are found to be in general agreement, and the C-12/C-13 ratio in all the examined stars is shown to be considerably lower than the solar-system value. It is suggested that these stars were formed from clouds with a C-12/C-13 ratio of 40 to 89 and that their atmospheres now exhibit an enhancement of C-13 abundance due to internal production and mixing to the surface.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 210; Dec. 15
    Format: text
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  • 7
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    The relation between carbon monoxide emission and visual extinction in cloud L134 (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Emission from the J = 1-0 transition of carbon monoxide has been mapped over an area of 40 by 55 arcmin in cloud L134, and visual extinctions over the entire cloud have been obtained by means of star counts. Line intensities of at least 2 K are observable down to an extinction level of about one magnitude. From observations of the J = 1-0 transition of the (C-13)O isotopic species at 18 locations in the cloud, a linear correlation is found between the local thermodynamic equilibrium (LTE) column densities of (C-13)O and magnitudes of visual extinction.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 210; Dec. 15
    Format: text
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  • 8
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    Stellar model chromospheres. V - Alpha Centauri A /G2 V/ and Alpha Centauri B /K1 V/ (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Models for the upper photospheres and lower chromospheres of Alpha Centauri A and B are derived from high-dispersion spectrograms of the Ca II K-line emission cores and damping wings. Effective temperatures, surface gravities, and ages consistent with the measured broadband colors, metallicities, and absolute magnitudes are estimated for the two stars. The spectrograms are calibrated by fitting the far-wing K profiles with synthetic fluxes based on radiative-equilibrium models, and the model atmospheres are obtained through a partial-redistribution analysis of the line cores and damping wings. These models are compared with those previously proposed for Procyon, Arcturus, and the sun. Many features in all the models are found to be quite similar, and some evidence suggests that Alpha Cen A may be significantly older and more evolved than the sun, even though both stars exhibit similar chromospheric properties.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 210; Nov. 15
    Format: text
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  • 9
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    Further joint X-ray, infrared, and radio observations of Cygnus X-3 (1976)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Observations of Cygnus X-3 have been carried out at 2.5-7.5 keV, 2.2 micrometers, 8.1 GHz, and 2.7 GHz over a two week period. The X-ray data show the periodic structure which is typical of Cyg X-3. At times the X-ray and infrared measurements show very similar periodic structure, both in phase and in shape, while at other times the infrared data show no periodic variability. The radio fluxes were unusually low during the period of observation; both the daily average radio flux levels and the spectral index remained nearly constant.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; 207; July 1
    Format: text
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  • 10
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    Evidence for a 17d periodicity from Cyg X-3 (1976)
    In:  CASI
    Details
    Publication Date: 2006-04-18
    Description: Data which indicate a periodicity of 17d from Cyg X-3 are reviewed. The data are taken from the Ariel 5 satellite All-Sky Monitor and the Sky Survey Experiment.
    Keywords: ASTROPHYSICS
    Type: X-ray Binaries; p 245-253
    Format: text
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