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  • Analytical Chemistry and Spectroscopy  (840)
  • ASTROPHYSICS  (546)
  • ASTRONOMY  (473)
  • 1980-1984  (1,859)
  • 1960-1964
  • 1955-1959
  • 1925-1929
  • 1982  (1,859)
  • 1925
Collection
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  • 1980-1984  (1,859)
  • 1960-1964
  • 1955-1959
  • 1925-1929
Year
  • 101
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    The peculiar UV extinction of Herschel 36 (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The differential extinction curve of Herschel 36 was determined from International Ultraviolet Explorer data. It is quite unusual, characterized by a distinct 2200 A peak with a very low far blue end at 5 to 7 mu to the -1 power. The star appears to be an extreme member of the group Savage drew attention to, previously consisting only of theta Ori, NU Ori, sigma Sco, and rho Oph. It appears that multiple scattering effects are needed to explain the observations.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 413-415
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  • 102
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    CNO abundances in H II regions of the Magellanic clouds and the galaxy with implications regarding the nucleosynthesis of the CNO element group (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Final abundance results of IUE observations of the UV spectra of three H II regions in the Small Magellanic Cloud and four H II regions in the Large Magellanic Cloud are presented. Calculated yields of carbon and oxygen derived are y(C)=.00063 and y(O)=.0016. The nucleosynthetic origin of nitrogen was evaluated as being predominantly a secondary element produced from carbon as its seed. Plotting log N/C versus log C/H yielded the rather unexpected result that log N/C decreases with lo C/H over the SMC-LMC-Orion range. The cause of this relationship is discussed.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 385-388
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  • 103
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    The far ultraviolet spectroscopic explorer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The scientific objectives and performance characteristics of a new astronomy mission referred to as the far ultraviolet spectroscopic explorer, or FUSE are being defined by a team involving people experienced instrumental requirements that best meet the scientific needs. The team is intended to have a lifetime of about one year, ending with the submission of a report to NASA which could be used as the basis for an engineering design study. The principal objective of FUSE is to obtain astronomical spectra at wavelengths shorter than is possible with the Space Telescope.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 345-346
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  • 104
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    Distribution of gas in the halo of the galaxy (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results are presented from a high-resolution, ultraviolet study of interstellar gas situated away from the plane of the Milky Way Galaxy, using the nuclei of Seyfert galaxies Mkn 509 and F9 as background probes. In these directions, low-velocity, galactic gas were detected as well as two extragalactic clouds, one probably associated with the Magellanic Stream and the other with Mkn 509. These data were combined with results from other lines of sight to show that the ultraviolet species extend about 10 kpc from the plane, assuming the high-latitude gas corotates with the galactic disk. Complimentary observations of the optical Ca II and Na I species suggests that these do not extend as far - perhaps 2 to 3 kpc from the plane. Further, the exceedingly complex velocity structure found only in Magellanic Cloud directions suggests that these sight-lines are not typical of high-latitude gas in general.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 359-362
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  • 105
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    IUE data reduction: Wavelength determinations and line identifications using a VAX/750 computer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A fully automated, interactive system for determining the wavelengths of features in extracted IUE spectra is described. Wavelengths are recorded from video displays of expanded plots of individual orders using a movable cursor, and then corrected for IUE wavelength scale errors. The estimated accuracy of an individual wavelength in the final tabulation is 0.050 A. Such lists are ideally suited for line identification work using the method of wavelength coincidence statistics (WCS). The results of WCS studies of the ultraviolet spectra of the chemically peculiar (CP) stars iota Coronae Borealis and kappa Camcri. Aside from confirming a number of previously reported aspects of the abundance patterns in these stars, the searches produced some interesting, new discoveries, notably the presence of Hf in the spectrum of kappa Camcri. The implications of this work for theories designed to account for anomalous abundances in chemically peculiar stars are discussed.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 326-330
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  • 106
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    On the correlation between chromospheric and coronal emission (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is shown that with increasing stellar activity the emission of the transition region and corona increases faster than the emission of the chromosphere. It is also explained why the pressure of the transition region increases with increasing stellar activity. Further, it is shown that this relation is a necessary requirement for the global stability of the chromosphere/transition region/corona system.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 268-272
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  • 107
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    The ultraviolet spectra of R and N type stars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Low dispersion long wave radiation spectra of three early N-type carbon stars (BL Orionis, TX Piscium and T Indi) obtained with the IUE are discussed. N-star spectra were compared with IUE observations of late M-type stars and several differences were noted. The Mg II and C II chromospheric emission lines reported are the first convincing detection of a 10,000-20,000 K chromosphere in the N stars.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 255-258
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  • 108
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    Discrepant asymmetry stars: The role of unsteady magnetic flux loops in the atmospheres of late-type giant stars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A number of spectroscopic peculiarities of K giants and other stars which lie in a wedge in the HR diagram are discussed. These peculiarities can be understood in terms of unsteady magnetic flux loops emerging into the stellar atmosphere from beneath the surface.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 235-238
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  • 109
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    An IUE survey of the Hyades star cluster (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: To date 11 of the brightest X-Ray stars (F-K dwarfs) in the Hyades have been observed with the IUE satellite with the short wavelength spectrograph. The IUE results and the X-Ray observations from the Hyades survey with the Einstein Observatory were combined. The differential emission measure function was estimated for each of the 7 stars which showed evidence of emission lines. Constraints on stellar atmospheric parameters (chromospheric pressure, coronal temperature and filling factor were derived. The implications of these results in the context of loop models for the corona and transition region (TR) of these stars are discussed.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 239-242
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  • 110
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    Synoptic studies of chromospheric variability in F - K dwarfs with the IUE (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Time-sequential series of IUE spectra for ten F, G and K dwarfs were obtained in 1980 and 1981 to study the rotational dependence of chromospheric flux in the ultraviolet. An interactive computational method using unbiased estimators was developed to measure emission line fluxes free of arbitrary judgement concerning the behavior of the underlying spectrum and shapes of the line profiles. Due to the limited number of observational samples per star, we have used special techniques to analyze the sparsely and anharmonically sampled emission line flux data. Two different autocorrelation measures were computed for each emission line as a function of temporal frequency. Examples and results of this analysis now in progress are given for several stars.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 227-230
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  • 111
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    Changes in the UV spectrum of HD 4174 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is noted that the symbiotic-like object HD 4174 (EG And) exhibits the optical spectrum of an M2 giant star, but also shows Balmer and nebular line emission. The first UV spectrum showed an intense far UV emission line spectrum typical of many symbiotic stars. A 470 day binary or pulsation period for this system, based on the changing strength and velocity of the H alpha emission. Preliminary indications are that the H alpha and far UV continuum are eclipsed near phase 0.6 (at maximum H alpha redshift), but that the correlation for the emission lines remains unclear and requires additional observations.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 219-222
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  • 112
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    Multifrequency observations of the quasar 1156+295 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The recent outburst in the quasar 1156+295 was discovered in the course of optical monitoring made in preparation for IUE observations in April 1981. Short and long wavelength spectra were obtained on three occasions when the object was very bright, and which were separated in time by intervals of 4 and 60 days. The UV continuum in all cases is a steeply falling power law, with slope close to -2.0. No spectral features are apparent in the UV. Closely simultaneous observations were made by our collaborators at radio, infrared, and optical frequencies. The continuum is less steep at optical and infrared frequencies, and the overall spectra show little change in shape with time.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 201-204
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  • 113
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    Four years of IUE research on clumpy irregular galaxies (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: During the first four years of IUE operations seven shifts were used to observe 4 clumpy irregular galaxies: Markarian 7, 8, 297, and 325. All spectra were obtained at low resolution in both short and long wavelength, with exposure time ranging from half to a full shift. The IUE spectra of clumpy irregular galaxies show that the clumps contain a very large number of early O and B type stars, with a large number of supergiants with respect to the main sequence stars. Possibly Wolf-Rayet stars and massive objects of the type of R 136a could also contribute to the clump luminosity. On the average, each clump radiates in the UV 100 times more than 30 Dor. On the other end the liner dimension of a clump is not much larger than the one of 30 Dor.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 156-159
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  • 114
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    IUE observations of symbiotic stars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The main photometric and spectroscopic characteristics in the ultraviolet and visual range of the most extensively studied symbiotic stars are reviewed. The main data obtained with IUE concern: (1) the determination of the shape of the UV continuum, which, in some cases, proves without doubt the presence of a hot companion; and the determination of the interstellar extinction by means of the lambda 2200 feature; (2) the measurement of emission lines, which enables us to derive the electron temperature and density of the circumstellar envelope, and, taken together with those lines observed in the visual, give more complete information on which spectroscopic mechanisms operate in the envelope; (3) the observation of absorption lines in the UV, which are present in just a few cases.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 89-101
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  • 115
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    Ultraviolet observations of interstellar dust (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A large fraction of astronomical observations in the UV are affected by extinction due to interstellar dust in the line of sight. The shape of the extinction curve varies markedly around the sky, especially in regions of nebulosity such as the Orion Nebula. The variations of the shape provide clues to the nature of the dust. Additional insight into the physical properties of dust can be obtained from reflected UV starlight as observed in NGC7023 by IUE and in the faint arms of M101 as photographed by a sounding rocket.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 68-79
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  • 116
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    Isolated grain condensation behavior: Computation methods and first results (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A set of efficient programs for calculation of condensation behavior in a system with either solar or carbon-rich elemental composition was developed to treat the course of condensation at very low pressures. These programs were applied to the problem of condensation at very low pressures. The minerals produced in the stellar and nova-related processes under study, including carriers of important volatile elements such as carbon and nitrogen, are candidates for accretion into meteorite parent bodies and planets, and may still be discernible in the enstatite chondrites.
    Keywords: ASTROPHYSICS
    Type: Planetary Atmospheres Program; p 36-47
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  • 117
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    Theory of electron-positron showers in double radio sources (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A black hole of mass of about 300 million solar masses is assumed to be present in the nucleus of an active galaxy or quasar. With an axial magnetic field near 1000 gauss, a potential drop 10 to the 19th volts is generated by the unipolar induction of a rotating accretion disk surrounding the black hole. The possibility that the acceleration of electrons or positrons in the unipolar fields initiates an electromagnetic cascade shower at distances at least 10 to the 16th cm from the black hole is investigated. The scattering medium for the shower is considered to be the spectrum of low energy photons originating from the inner region of the disk. It is found that at completion of the cascade, power-law energy spectra of relativistic electrons and positrons and of gamma-rays emerge under appropriate conditions. If the cascade-initiating particles are collimated, the electrons and positrons emerge in a collimated beam. Such beams may power extragalactic double radio sources.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 262
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  • 118
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    Further morphological studies of QSOs (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results are presented of optical mapping of 29 QSOs, together with results of VLA observations of 16 of the optically observed objects. Principal results are that QSOs to z = 0.45 have extended nebulosity, the average ratio of nuclear to fuzz luminosity, corrected for resolution, is about 0.5, some 8 times higher than Seyfert I values, the average fuzz luminosity is -21.5, fainter than giant ellipticals, and fuzz morphology does not resemble E or S galaxies, but is very similar to Seyfert I's to similar luminosity limits. In some cases, indications of spiral structure are seen, and a large fraction of asymmetrical morphology is noted. In the QSO 0241 + 622, steep spectrum radio emission is found displaced from the central source exactly along the minor optical axis.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 262
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  • 119
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    Space Telescope - Eye on the universe (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The NASA Space Telescope, which is to be put into orbit by the Space Shuttle in 1985, is described with attention to the design characteristics and fabrication processes of its optics and the five scientific instruments that will be mounted at the focal plane, behind the primary mirror. The primary mirror is fabricated from Ultra Low Expansion Glass, weighed 907 kg as a blank and took three and a half years to grind and polish to a deviation of no more than 0.000025 mm from the ideal surface. The instruments carried are the Wide Field Planetary Camera, which employs CCD detectors, the Faint Object Camera, the Faint Object Spectrograph, for use at visible and UV wavelengths, the UV High Resolution Spectrograph for 1100-2300 A wavelengths, and the High Speed Photometer for the study of time-dependent brightness fluctuations.
    Keywords: ASTRONOMY
    Type: Spaceflight; 24; Dec. 198
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  • 120
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    The WC6 star HD76536 compact companion (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The variability of HD76536 was observed by IUE. Photometric variability is confirmed by measurements with the IUE fine error sensor. Profile changes in the ultraviolet emission lines and stellar wind absorptions were studied. Data favor a binary model with a low luminosity (perhaps compact) secondary.
    Keywords: ASTROPHYSICS
    Type: ESA 3rd European IUE Conf.; p 269-271
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  • 121
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    On redistribution and the equations for radiative transfer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The derivation of the equations of statistical equilibrium are outlined, starting from the quantum density-matrix equations, drawing particular attention to the approximations and assumptions used in the development of tractable expressions. Then, using the quantum-fluctuation-regression theorem, emission and absorption coefficients are obtained for multilevel atomic systems which are nondegenerate except for m-substates. These coefficients are valid to first order in the incident intensity. Possible extensions to higher intensity broadband incoherent fields are suggested.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 260
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  • 122
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    Neutral hydrogen in elliptical galaxies with nuclear radio sources and optical emission lines (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-22136)
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 259
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  • 123
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    Sensitive ammonia observations in the southern hemisphere (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The 64-m spacecraft communication antenna of the NASA-JPL Deep Space Network has been equipped for spectral line observations at K band (18-25 GHz). To demonstrate the potential of this system, preliminary observations of the (1, 1) transition of ammonia are reported for a selection of eight southern molecular clouds. Estimates of gas density and ammonia column density are reported for six sources.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 87; Aug. 198
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  • 124
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    A search for fragmentation debris near Ursa Major Stream stars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Accretion models of planet formation and the early cratering history of the solar system suggest that planet formation is accompanied by a cloud of debris resulting from accumulation and fragmentation. A rough estimate of the infrared luminosities of debris clouds is presented for comparison with measured 10-micron luminosities of young stars. New measurements of 13 F, G, and K main-sequence stars of the Ursa Major Stream, which is thought to be about 270-million years old, place constraints on the amount of debris which could be present near these stars.
    Keywords: ASTROPHYSICS
    Type: Icarus; 50; Apr. 198
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  • 125
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    Space infrared astronomy - Overview of NASA planning (1982)
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    Publication Date: 2011-08-18
    Description: The present status and potential future direction of the NASA space infrared astronomy program is reviewed. Projects and project concepts discussed include the Infrared Astronomy Satellite, Small Infrared Telescope on Spacelab 2, Cosmic Background Explorer, Shuttle Infrared Telescope Facility, Space Telescope, large deployable reflector, molecular line survey, and infrared interferometer in space. Needs for continued engineering development in critical technology areas such as detectors, cryogenics, optics, and space structures are indicated.
    Keywords: ASTRONOMY
    Type: Optical Engineering; 21; July-Aug
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  • 126
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    Large-scale magnetic fields in spiral galaxies (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The optical polarization vectors which measurements have shown to be parallel to the pronounced dark lanes of such galaxies as NGC 5128 and 4590 are interpreted as the consequence of a large scale, systematic field parallel to the dark lane that leads to the alignment of the grains. It is suggested that such polarization may also be produced by scattering off grains concentrated in the dark lane. It is recommended that there be further observational tests of the hypothesis that the observed polarization indicates the magnetic field in the galaxy.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 258
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  • 127
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    Halley's Comet (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Since 240 B.C., Chinese observers have documented a nearly unbroken record of scientifically useful observations of Periodic Comet Halley (P/Halley). Investigations of the comet's motion by Western astronomers are discussed, taking into account the first successful prediction of a cometary return by Halley (1705), computations conducted by Rosenberger (1830), and studies performed by Cowell and Crommelin (1910). Comet Halley's motion and nongravitational forces are considered along with meteor showers associated with P/Halley. The physical properties of P/Halley are examined, giving attention to the visual observations, the light curve of P/Halley, the coma, the tails, direct photographs, spectrograms, and the emission spectrum of P/Halley. Other subjects explored are related to the cometary nucleus, the mass of P/Halley, the rotation period and axial inclination, the composition, a nominal model of P/Halley's coma, and plans for investigations in connection with the coming apparition of Comet Halley.
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  • 128
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    Observations of Paschen alpha in the broad-line radio galaxy 3C 445 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: P alpha line flux measurements of the broad-line radio galaxy 3C 445 made at the NASA IR Telescope Facility in September 1981 are discussed. Broad-band measurements were obtained at H of 1.65 micron and K of 2.2 microns. A line flux of P alpha was found at 3.4 times 10 to the -13th ergs/sq cm sec. No discernable variation was detectable regarding measurements made in 1976. Substantial reddening was concluded to exist, although the H gamma lines observed were not due to reddening. The total H alpha luminosity was determined to be 4 x 10 to the 43rd ergs/sec. Steep Balmer line decrements are concluded to be due to interposed dust.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 256
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  • 129
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    HEAO 1 measurements of the galactic ridge (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-20097)
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 255
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  • 130
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    Comparison of starting values for iterative solutions to a universal Kepler's equation (1982)
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    Publication Date: 2011-08-18
    Description: General starting values for the iterative numerical solution of a universal Kepler's equation for position in a conic orbit at a specified time are investigated. Three starting values based on recent refinements of previously obtained bounds on the solution are derived and tested numerically. Of these, a simple starting value based on a cubic approximation to Kepler's equation provides the most rapid convergence using both first and second order Newton algorithms. The performance of the starting values are compared with similar studies which used the restricted case of elliptical orbits with the initial epoch at periapse.
    Keywords: ASTRONOMY
    Type: Journal of the Astronautical Sciences; 30; Jan
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  • 131
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    Cygnus X-3 observed at photon energies above 500 GeV (1982)
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    Publication Date: 2011-08-18
    Description: High-energy gamma rays from Cyg X-3 have been observed with the twin 11-m mirrors of NASA JPL's solar energy facility, using the atmospheric Cerenkov technique, resulting in data from about 100,000 air shower events with an approximate threshold energy of 500 GeV for the August 29 to September 6, 1981 period. A positive signal whose amplitude is 10.9 + or - 2.5% of the background cosmic ray rate appears near phase 0.6 of the 4.8-hour cycle, where phase 0.0 corresponds to minimum X-ray emission. This, together with previous Cerenkov detections, indicates that the high energy emission from Cyg X-3 is evolving on a time scale of a few years and suggests that the present form of the system has a recent origin.
    Keywords: ASTROPHYSICS
    Type: Nature; 296; Apr. 8
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  • 132
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    Parity nonconservation and the origin of cosmic magnetic fields (1982)
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    Publication Date: 2011-08-18
    Description: Three mechanisms of cosmic magnetic field generation are discussed: (1) asymmetric decay of particles emitted by rotating black holes; (2) asymmetric proton emission by black holes due to weak radiative corrections, and (3) equilibrium parity-violating currents. It is shown that all three mechanisms can produce a seed field sufficiently strong to account for the present galactic fields.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 254
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  • 133
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    Cometary NH - Ultraviolet and submillimeter emission (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A description is presented of the results of computer calculations on the molecule NH, which is an important constituent of cometary comae, and a probable, but an as yet undetected, interstellar species. Attention is given to spectroscopic properties, the treatment of solar spectral data, and radiative transfer calculations. The results of calculations for the Einstein A-coefficients are given in an appendix, where the entries for the X-X and A-A transitions depend on the assumed permanent electric-dipole moment squared. Rotational-spin-Lambda-doublet energy levels used for statistical equilibrium population densities are listed in a table.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 253
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  • 134
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    Interplanetary gas. XXVIII - A study of the three-dimensional properties of interplanetary sector boundaries using disconnection events in cometary plasma tails (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Studies of the solar wind on the basis of cometary plasma tail observations are considered. Niedner and Brandt (1978, 1979) have concluded that the plasma tail frequently disconnects from the cometary head, and that these disconnection events (DEs) are produced by magnetic reconnection at sector boundary passages. They proposed that the disconnections are a natural combination of Alfven's model and the solar-wind sector structure first discovered by Wilcox and Ness (1965). The DEs can be utilized as probes of interplanetary sector structure. Correlations between DEs and sector boundaries observed at earth are considered, and sector boundary properties deduced from DEs are discussed. Attention is given to a review of the warped sheet model, the latitude extent of sector structure, the sector boundary tilt, and specific sources of error in the tilt angles derived from DEs.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal Supplement Series; 48; Jan. 198
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  • 135
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    Radial widths, optical depths, and eccentricities of the Uranian rings (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of the stellar occultation by the Uranian rings of 15/16 August 1980 are used to estimate radial widths and normal optical depths for segments of rings 6, 5, 4, alpha, beta, eta, gamma, and delta. Synthetic occultation profiles are generated to match the observed light curves. A review of published data confirms the existence of width-radius relations for rings alpha and beta, and indicates that the optical depths of these two rings vary inversely with their radial widths. Masses are obtained for rings alpha and beta, on the assumption that differential precession is prevented by their self-gravity. A quantitative comparison of seven epsilon-ring occultation profiles obtained over a period of 3.4 yr reveals a consistent structure, which may reflect the presence of unresolved gaps and subrings.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 87; Feb. 198
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  • 136
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    On syntheses of the X-ray background with power-law sources (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The conditions under which the combined emission from power-law sources can mimic the X-ray background (XRB) spectrum in the 3-50 keV range are considered in view of HEAO 1 A-2 experiment measurements, and it is confirmed that a good fit may be obtained. The required spectral properties of the component sources differ, however, from those observed for local active galactic nuclei. Constraints are deduced for both the low-luminosity extension and evolution of such local objects, and it is shown that any other class of sources contributing to the X-ray background must be characterized by an energy spectral index lower than about 0.4, which is the mean index of the XRB, and exhibit steeper spectra at higher energies.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 253
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  • 137
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    Hot wind from Gamma/2/ Velorum observed in the ultraviolet carbon lines (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The close binary system Gamma(2) Vel, consisting of a WC8 and an O9 I star, has been observed in the ultraviolet at various phases. Preliminary analysis of selected data shows that the temperature of the stellar wind from this binary increases outward. This suggests that an additional source of energy other than radiation pressure may exist for the wind. The mass flow occurs in all directions from the binary. However, there is evidence of an increase in the mass flow through the third Lagrangian point, although from the extant data it is not possible to decide whether or not a similar increase in the mass outflow occurs through the second Lagrangian point. There is also evidence of mass surge, which probably is independent of orbital phase.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 252
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  • 138
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    Neutral hydrogen emission and absorption in three active Irr II galaxies (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Peak optical H I absorption depths of 10% are found in a neutral hydrogen emission-absorption study of the active-nucleus Irr II galaxies NGC 520, 5363, and 5506. It is suggested that the absorption is due to a few standard clouds within several hundred parsecs of the nucleus, in the narrow-line emission region. The width of the absorption features is interpreted as being due to random motions of the gas within the absorbing clouds, in contrast to the large widths of the emission features that are due to the overall rotation of the galaxy.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 252
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  • 139
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    Vacuum deposition of iridium on large astronomical mirrors for use in the far UV (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An iridium coating has been deposited by electron-beam evaporation on a 0.91-m mirror which serves as the telescope primary of a sounding rocket instrument for far-UV spectrometry. The evaporation was carried out by applying 8 kV at 400 mA to the electron gun. Zone refined Ir of 99.99% purity was used, and the electron beam was electromagnetically swept over the surface of the evaporant. Under these conditions, deposition rates of 0.55 A/sec were achieved. The reflectance distribution achieved at a wavelength of 584 A was extremely uniform; the mean reflectance was 21.2% with a standard deviation of only 0.3%. This represents a substantial improvement over Al + MgF2 and Al + LiF coatings for applications involving multiple reflections and weak signals, as might be expected in a high-resolution spectrograph studying distant celestial objects.
    Keywords: ASTRONOMY
    Type: Applied Optics; 21; Jan. 1
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  • 140
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    Current NASA studies for a Far Ultraviolent Spectrographic Explorer (FUSE) (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The NASA plans for FUSE, a satellite which obtains spectra with resolutions between 100,000 and 100 in the spectral regions from 912 to 1216A and 100 to 912A, are outlined. Scientific problems which can be tackled by FUSE, but not by IUE or the Space Telescope, are discussed. A grazing incidence echelle and a hybrid echelle design are presented. They have high throughput, large simultaneous spectral range, and low background photon counting statistics. The satellite operational organization is similar to that of IUE.
    Keywords: ASTRONOMY
    Type: ESA 3rd European IUE Conf.; p 473-485
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  • 141
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    The observed properties of X-ray pulsars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A unified description of the properties of the 14 X-ray pulsars is summarized. Properties of X-ray pulsars and obvious correlations with luminosity are outlined.
    Keywords: ASTRONOMY
    Type: Max-Planck Inst. Phys. and Astrophys. Accreting Neutron Stars; p 29-40
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  • 142
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    The remarkable 400 micron source NGC 6334/I/North/ (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations at 400 microns of the NGC 6334 complex have confirmed the discovery of an unusual 1000-solar mass object, NGC 6334/I(North), which was not detected by broad-band 100-micron survey observations. The results suggest that this cool source (T = 19 + or - 5 K) is an active star formation region in a very early stage of evolution. The observed infrared luminosity of the source, 7000 solar luminosities, requires the presence of one or more embedded B stars or the formation of a dense protostellar core. Derived dust and gas densities agree well with results from molecular line observations of the complex. Nearby 100 micron peaks I and V were also observed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 259
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  • 143
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    The path and surviving tail of a comet that fell into the sun (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A satisfactory orbital solution for Comet Howard-Koomen-Michels 1979 XI is found on the assumption that the comet's line of apsides coincided with that of the Kreutz sungrazing comet group. The derived perihelion distance then shows that this is the first known case of a comet falling into the sun. A dust tail that survived the comet is studied as a particle flow phenomenon controlled by no force other than solar gravity and solar radiation pressure. The tail's outline is interpreted in terms of an onset of dust production, a peak repulsive force on the particles, and a circumsolar dustfree zone due to particle sublimation. It is shown that the surviving debris consisted mostly of absorbing, submicron size particles in hyperbolic trajectories convex to the sun and curving toward the earth. The tail width may be a product of the interaction of charged dust in the tail with a complicated structure of the coronal magnetic field.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 87; July 198
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  • 144
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    Extragalactic gamma radiation - Use of galaxy counts as a galactic tracer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-20109)
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 109; 2, Ma; May 1982
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  • 145
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    The light curve of periodic comet Halley 1910 II (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Photometric parameters for periodic comet Halley 1910 II have been derived from 144 total visual magnitude estimates. The pre-perihelion data are best represented by an absolute magnitude of 5.47 and a power-law exponent of 4.44; post-perihelion results show that the absolute magnitude brightened to 4.94, and the exponent decreased to 3.07. Only small fluctuations in brightness about the power-law solutions are noted. Based on these results, a forecast of the visual brightness of periodic comet Halley's 1985-1987 apparition is presented.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 87; June 198
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  • 146
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    Large-scale variations of the interplanetary magnetic field - Voyager 1 and 2 observations between 1-5 AU (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-13594)
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 87; June 1
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  • 147
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    Accretion disk coronae (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-20106)
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 257
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  • 148
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    The interstellar spectrum of the supernova 1980k in NGC 6946 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Bright supernovae in external galaxies offer a rare opportunity to probe the intervening interstellar media over very extended path-lengths, including the disk and halo of the Galaxy and the parent galaxy of the supernova. SN 1980k was discovered in NGC 6946 on 1980 October 29. In the first month after discovery, high resolution optical and ultraviolet observations were obtained to exploit the supernova as a probe of the intervening interstellar media. The obtained data are discussed. In the spectra, absorption lines were observed of Mg I, Mg II, Fe II, Mn II, Ca II and Na I. The absorption lines are attributed to the intervening interstellar media distributed over the very extended line of sight sampled, of order 7 Mpc. These lines are wider and stronger than any previously measured in the quiescent interstellar gas in the halo and disk of the Milky Way and of external galaxies
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society; vol. 199
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  • 149
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    Solar-stellar astrophysics (1982)
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    Publication Date: 2011-08-18
    Description: Nonthermal physical processes in the solar atmosphere are discussed. The solar atmospheric regions are defined, and solar convection and its phenomena are explained. The relationship of the solar dynamo, magnetic field, and flares is explored. The solar atmospheric velocity fields are discussed, and the unresolved problem of the nature of atmospheric heating is detailed. The solar wind heating and acceleration are discussed and the need for global solar atmospheric models is emphasized. The application of these solar nonthermal processes to the stars in general is then taken up, employing the same categories as were applied to the solar atmosphere.
    Keywords: ASTROPHYSICS
    Type: Comments on Modern Physics; vol. 9
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  • 150
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    Energy distribution in the strongly interacting binary system SX Cassiopeiae (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: IUE spectra and optical scans covering the 110-680 nm interval were obtained in a search for a source which would resolve the anomalous presence of strong Balmer emission lines in the SX Cas eclipsing binary system, which is inconsistent with the usual spectral classification of the components as A6 III + G6 III. The IUE spectra unexpectedly show such strong emission lines as those of C IV, N V and Si IV, which require higher temperatures that the already anomalously high Balmer lines, and a continuum several magnitudes higher than the extrapolated continuum of an A6 star. A model in which the UV continuum originates in the transition zone between the A6 star and an accretion disk fails to reproduce the observed energy distribution. A revision of component spectral types to B7 + K3 III removes the UV excess.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 256
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  • 151
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    Apparent superluminal motion in the quasar NRAO 140 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Very long baseline interferometer (VLBI) measurements of the compact radio structure in the quasar NRAO 140 (z = 1.258) have been obtained at three epochs at a wavelength of 2.8 cm. These observations indicate that the two most compact radio components are separating at an angular rate of 0.10-0.14 milli-arcsec per year. For cosmological distances H sub 0 = 50 and q sub 0 = 0, this corresponds to a velocity of separation (in the quasar's rest frame) of 10 + or - 2 times the speed of light, c; for H sub 0 = 100 and q sub 0 = 1, the value is (3.1 + or - 0.6) c. Other interpretations of the temporal changes in correlated flux density and closure phase are discussed and are considered unlikely. The derived velocities are consistent with an earlier prediction that the separation velocity should be greater than about 4 c. Extrapolation back to the epoch of zero separation indicates that the expansion originated between late 1963 and late 1968 (under the assumption of constant velocity). This range includes the beginning of an isolated outburst in flux density at 2.8 cm. These results cannot be used to make any statements concerning the validity of cosmological interpretations of QSO redshifts.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 255
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  • 152
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    Rotational temperatures of cyanodiacetylene in Sagittarius B2, TMC-1, and IRC +10216 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 254
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  • 153
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    Observation of two gamma-ray bursts by Vela X-ray detectors (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Bursts of X-rays coincident in time with two gamma-ray burst events were observed by the 3-12 keV collimated X-ray detectors on the Vela spacecraft. Both of these observations show recurrence on a time scale of hundreds of seconds. For one of these events (GB 720514) the X-ray detection gives an improved position as well as information on the spectrum late in the outburst. The other event (GB 740723) is of special interest because the source, not previously located, is consistent in direction with the binary pulsar SMC X-1 in the Small Magellanic Cloud; this is the first moderately small error box for a gamma-ray burst to contain a strong X-ray source.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 254
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  • 154
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    The local interstellar medium (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Analysis of the velocities of optical interstellar lines shows that the sun is immersed in a coherently moving local interstellar medium whose velocity vector agrees with that of the interstellar wind observed through backscatter of solar H Ly-alpha and He lambda 584 photons. The local interstellar medium consists of both cool clouds and warm intercloud medium gas, has a mass of perhaps approximately 30 solar masses, does not have severe depletion of trace elements from the gas phase, and appears to be material which has been shocked and accelerated by stellar winds and supernovae associated with the Sco-Oph OB association.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 254
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  • 155
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    The ultraviolet spectrum of the Crab Nebula (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Ultraviolet spectroscopy of the Crab Nebula done by the International Ultraviolet Explorer satellite is described, and an estimate of the carbon abundance is made, noting data reduction to remove spectral defects caused by radiation hits. The important C IV 1549, He II 1640, and semiforbidden C III 1908 emission line intensities were measured and upper limits placed on other ultraviolet features for the brightest filamentary region in the Nebula. The emission lines imply an average ionic abundance ratio n(C+2)/n(O+2) in the range from 0.4 to 1.5 in the observed gaseous condensations. The elemental abundance ratio of carbon to oxygen is probably in the same range. Analysis shows that there is no perceptible excess of carbon due to presupernova nucleosynthesis in the observed region. The large helium abundance, small carbon and oxygen abundances, and presence of a neutron star in the Crab Nebula suggest that the presupernova star had a mass close to eight solar masses.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 253
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  • 156
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    4C 18.68 - A QSO with precessing radio jets (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High-resolution VLA radio maps at 20 cm and 6 cm wavelengths of the quasar 4C 18.68 reveal an extended halo of about 20 arcsec containing complex curved structures extending east and west from the central source. The central source has a flat spectrum, while the spectrum generally steepens with distance from the center of the structure. The details of the structure and polarization of the emission suggest relativistic ejection in opposing directions by a precessing or rotating double jet with a period of about 50,000 years, consistent with the presence of two interacting massive bodies in the central source.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 253
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  • 157
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    On the folding phenomenon of comet tail rays (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is shown that the folding phenomenon of the comet tail rays is compatible with the Ferraro isorotation law if the comet tail magnetic field has no azimuthal component, that is, B sub phi (the polar angle) equals zero. Considering electric drift due to convectional electric fields, a formula is obtained for the angular rate of a ray closure which reduces to that of Ness and Donn (1966) if the velocity profile across the tail is linear. The magnetic field B of approximately 20-40 gammas in the coma and less than about 10 gammas in the distant tail is estimated under typical solar wind conditions at 1 AU.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 198
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  • 158
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    Development of a 1m-normal-incidence-EUV-Telescope (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A brief description is given of the 1m-EUV-Telescope and its focal plane instrumentation, namely an EUV spectrometer and six EUV/FUV photometers. The telescope is scheduled for launch on an Aries rocket on June 17, 1982. The principal goals are the white dwarf HZ43 and a photometric scan across the sky in an area of the sky where 21 cm line observations reveal a steep density gradient. The optical bench of the telescope is a cylinder made of a graphite epoxy compound. Despite its low specific weight, the bench shows an excellent mechanical performance, with an elasticity modulus of approximately 70,000 N/cu mm. It is pointed out that by carefully combining layers with different winding angles of the carbon fiber, the thermal expansion along the cylinder axis is almost negligible, even under severe thermal loads
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  • 159
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    The derivation of Halley parameters from observations (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Nominal value model parameters for the nucleus (size, mass, rotation, albedo, hydrogen production) the dust and gas for P/Halley at 0.9 AU postperihelion are derived from the light curve and spectra of Halley and by modeling the effect of the nongravitational forces, e.g., the outgassing rocket type effect of the nucleus. In those cases where Halley observations are not sufficient, the average value derived from a larger set of other comets is used, or data from comet Bennett, Halley's best analog, are taken. A flow diagram shows how the parameter values are derived and to what extent these derived values are interdependent. Previously announced in STAR as N82-23097
    Keywords: ASTROPHYSICS
    Type: (ISSN 0273-1177)
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  • 160
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    Einstein Observatory results on active galactic nuclei (1982)
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    Publication Date: 2011-08-18
    Description: The results of Einstein Observatory surveys of active galactic nuclei (AGN) are reviewed. The ubiquity of X-ray emission from AGNs was confirmed. The relations between X-ray and optical luminosities, between X-ray and radio properties, and between X-ray and optical-UV line emission found by the surveys are summarized and briefly discussed. The possible causes of observed X-ray emission from jets in Cen-A, 3C273, and M87 are considered. The active nucleus discovered in the optically 'dull' galaxy NGC 4156 is covered, and a model for NGC 4151 based on detailed spectral studies is briefly discussed. This model establishes the global symmetry of the AGN clouds, their approximate sizes, and their ionization state. Difficulties encountered in attempting to explain the cosmic X-ray background in terms of AGN contributions are addressed.
    Keywords: ASTROPHYSICS
    Type: (ISSN 0273-1177)
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  • 161
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    IUE observations of cataclysmic variables (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The four years of IUE operation have revealed that the ultraviolet region of the spectrum contributes a dominant share of the emerging energy from cataclysmic variables and provides important clues to the physical nature of these systems. The implications of the continuum flux distributions and line spectra for the determination of the accretion rates and mass loss rats are considered.
    Keywords: ASTROPHYSICS
    Type: (ISSN 0273-1177)
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  • 162
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    A search for frosts in Comet Bowell /1980b/ (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Infrared observations of Comet Bowell represent the first search for frost signatures in a comet beyond 2 AU from the sun. Broad- and narrowband photometry has been obtained as well as CVF spectrophotometry of this comet and there is no evidence for absorption features in the spectral area between 1.25 and 2.3 microns. Models of the coma have been generated which constrain the volatile content of the grains an; are in agreement with the observed albedo. The darkness of the coma particles at large heliocentric distances indicates a low albedo nucleus as well. Brightness variations during the observing period seem to indicate an active nucleus at 4.5 AU from the sun.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 87; Dec. 198
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  • 163
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    Spectroscopic equipment for the Space Telescope (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Space Telescope will provide views of the Universe of remarkable clarity. Central to its capabilities is an f/24 Ritchey-Chretien telescope with 40,000 sq cm unobscured collecting area, which will provide point-source images less than 0.1 sec in radius at wavelengths below 633 nm. It will operate over the range 110 nm to 1 mm. The initial flight instrumentation includes two spectrographs, the Faint Object Spectrograph (F.O.S.) and the High-Resolution Spectrograph (H.R.S.). The F.O.S. is sensitive from 115 to 800 nm. It will provide data at resolving powers 1000-100 on extremely faint sources. The H.R.S. operates at the wavelengths 107-320 nm. It will achieve high photometric accuracy at resolving powers 100,000, in the echelle mode, or 10,000-1000 in first order, on brighter targets. The two cameras on board the Space Telescope will provide ancillary spectroscopic capabilities.
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  • 164
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    A comparison of the X-ray properties of X Persei and Gamma Cassiopeiae (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The greater than 0.0001 solar mass/year loss rates required to power X-ray sources, if associated compact objects are white dwarfs, are many orders of magnitude greater than even the highest estimates for the main sequence Be stars Chi Per and Gamma Cas, confirming that the compact objects in these systems are neutron stars. While observed mass loss rates are of the order of that required to power the X-ray emission from a neutron star, X-ray measurements have established rates at least an order of magnitude above UV estimates, supporting earlier suggestions of an inclination dependence in the mass loss from rapidly rotating main sequence OB stars which results in mass loss rates in the orbital plane that are at least one order of magnitude higher, or terminal velocities that are at least a factor of 2.0 lower, than is indicated by UV measurements.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 263
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  • 165
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    Visual and infrared observations of the distant Comets P/Stephan-Oterma /1980g/, Panther /1980u/, and Bowell /1980b/ (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The paper reports combined visual imagery and spectroscopy, near-infrared spectroscopy, and broadband infrared photometry of comets P/Stephan-Oterma (1980g), Bowell (1980b), and Panther (1980u) at intermediate heliocentric distances. The visual data indicate the existence of solid grains in extended halos around the nuclei of the three comets. Broadband near-infrared and thermal infrared measurements of Comet Panther suggest the presence of 2-4-micron-radius particles in the coma which most likely contain molecules incorporating the N-H bond, but which are more complex and less volatile than NH3. Such molecules can be produced in the grains by cosmic-ray reprocessing. Near infrared spectral features identical to those seen in comet Panther similary suggest the presence of a molecule incorporating the N-H bond in comet Bowell.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 87; Dec. 198
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  • 166
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    The relationship between carbon monoxide abundance and visual extinction in interstellar clouds (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Carbon monoxide column densities are compared to visual extinctions toward field stars in the rho Oph and Taurus molecular cloud complexes. The relationship of C(0-18) column density to extinction is established, and new determinations for (C-13)O column densities are given for a range of visual extinctions extended to beyond 20 mag. A prescription for determining hydrogen column densities and masses of molecular clouds from observations of CO isotopes is presented and discussed critically. These measurements agree well with the predictions of gas phase chemistry models which include chemical fractionation and selective isotopic photodestruction. The functional dependence of the C(O-18) column density on extinction is characterized by two different regimes separated by a distinct transition observed to occur at 4 mag in both molecular cloud complexes, whereas the functional dependence of (C-13)O is quite different in the two regions. Some saturation is found to occur for C(O-18) emission at high visual extinction and use the rarer isotopic species C(O-17) and (C-13)(O-18) to correct for it.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 262
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  • 167
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    Relativistic precessing jets in quasars and radio galaxies - Models to fit high resolution data (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The formulation of generalized models tracing the geometry and intensity of the synchrotron emission from precessing, twin, relativistic jets as projected on the plane of the sky is presented. It is shown that neither the shape of the image nor its relative intensities are altered by including the effects of a cosmological redshift and a relative velocity between the source and observer. The models are fitted to the available data for several quasars and radio galaxies and demonstrate the plausibility of the phenomenon. Probable selection effects are considered and diagnostics given for recognizing objects showing this behavior. In the radio galaxies considered, velocities up to about 0.2c and precession periods of 1,000,000 yr are deduced. In the QSOs investigated, velocities of 0.7c and greater are found and periods of order 10,000 yr. In some cases precession cone angles increase with time. Consequences in terms of lifetimes of QSO behavior and binary supermassive objects are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 262
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  • 168
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    Global sensitivity to velocity errors at the libration points (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The global effects on non-linear stability are investigated at and around the triangular libration points. The model of the circular restricted problem of three bodies is used, considering the earth and the moon as the primaries. Areas of the initial conditions in the configuration space leading to stability with zero initial velocity around the equilibrium points are compared to stable areas in the phase space with variable initial velocity and zero initial deviations at the equilibrium points. The behavior of the system concerning errors due to initial conditions in the configuration space is studied for 6 years and the effects of initial velocity errors are considered for 7.73 years.
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  • 169
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    Observations and dynamics of plasma tails (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of plasma tails of comets are reviewed. The basic morphology of plasma tails is examined. It is shown that two features, viz., the ray-folding phenomenon and disconnection events, are essential to a general understanding of plasma tail phenomena. A qualitative model of disconnection events is proposed that is based on the cyclic occurrence of magnetic reversals in the solar wind.
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  • 170
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    Photochemical processes in the inner coma (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Models for the inner-coma chemistry of comets are reviewed. The physics relevant to the coma's chemistry is summarized, and the interaction of solar radiation with the coma is described, along with photolytic and chemical processes. The formation and destruction of several observed species are traced through a chemical reaction network, and model results are compared with observations. The species considered include CN, C2, C3, NH2, CH, CO, CO(+), OH, H2O, HCO, C2H4, and C2H3. The models most consistent with observations are shown to indicate that only trace amounts (2% in all) of molecules bearing CN, C2, C3, and NH2 can be present in the nucleus of a comet.
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  • 171
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    Abundances in five nearby galactic H II regions from infrared forbidden lines (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Airborne measurements of the Ar II (6.99 micron) and S II (18.7) micron lines for five compact H II regions in the solar neighborhood are presented, as well as 2-4 micron and 8-13 micron spectroscopy where available. From these data and radio data, lower limits to the elemental abundances of Ar, Ne, and S are deduced. Some of these H II regions suffer substantial nebular extinction, and some are extended. After correcting for beam size effects an extinction, it is found that four of the objects are consistent with standard abundances, within the uncertainties of correcting for unobserved ionization states. A Perseus arm object, S156, is apparently overabundant in sulfur.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 262
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  • 172
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    Turbulent compressible convection in a deep atmosphere. I - Preliminary two-dimensional results (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The turbulent convection of a compressible fluid in a deep atmosphere is simulated by two-dimensional numerical computations, displaying coexisting 'cells' whose sizes range from the total depth of the convection zone to the smallest scale height at the top. While the largest cells traverse the entire zone, smaller ones are clustered near the top. The vertical correlation length of the vertical velocity is proportional to the local pressure or density scale height, in a way reminiscent of the concept of mixing length.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 263
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  • 173
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    Detection of interstellar sodium hydroxide in self-absorption toward the galactic center (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A weak self-absorbed emission line, which is identified as the J = 4-3 transition of sodium hydroxide, has been detected in the direction of Sgr B2(OH). The correspondingly weak Sgr B2(QH) emission line U75406, previously reported as an unidentified spectral feature by other investigators, is consistent with the J = 3-2 transition of sodium hydroxide. This detection may represent the first evidence of a grain reaction formation mechanism for simple metal hydroxides. The detection of H62 Delta toward Orion A is also reported.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 262
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  • 174
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    Studies in astronomical time series analysis. II - Statistical aspects of spectral analysis of unevenly spaced data (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Detection of a periodic signal hidden in noise is frequently a goal in astronomical data analysis. This paper does not introduce a new detection technique, but instead studies the reliability and efficiency of detection with the most commonly used technique, the periodogram, in the case where the observation times are unevenly spaced. This choice was made because, of the methods in current use, it appears to have the simplest statistical behavior. A modification of the classical definition of the periodogram is necessary in order to retain the simple statistical behavior of the evenly spaced case. With this modification, periodogram analysis and least-squares fitting of sine waves to the data are exactly equivalent. Certain difficulties with the use of the periodogram are less important than commonly believed in the case of detection of strictly periodic signals. In addition, the standard method for mitigating these difficulties (tapering) can be used just as well if the sampling is uneven. An analysis of the statistical significance of signal detections is presented, with examples
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 263
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  • 175
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    Spectroscopy of two BL Lacertae objects (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: As part of a continuing program of observations of Bl Lac objects, the IUE cameras were used to look at PKS 0548-322 and PKS 2155-304. The spectra obtained are well described by power laws with alpha approximately 0.8 in each case. For each object, one set of simultaneous X-ray data was obtained using the solid state spectrometer (SSS) on the Einstein Observatory. These data show that the power law extends from ultraviolet frequencies into the X-ray regime, although it steepens slightly for PKS 2155-304. Both objects are variable in the ultraviolet and/or X-ray; in neither case does the small spectral variability appear to correlate with the intensity variability. The overall spectrum of these objects is interpreted in light of a synchrotron self-Compton model with relativistic beaming.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 177-180
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  • 176
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    Time variations in C IV lambda 1550 and Ly alpha emission lines in NGC5548 (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Two short-wavelength images of NGC5548 were obtained and separated by a three month interval. Combining this data with that obtained by Wu et al. One year prior to the first image, time variations were discovered in the C IV lambda 1550 and Ly alpha profiles as well as in the intensity ratio. In the image obtained in November 1980, the C IV profile is essentially the same as that of WU et al. However, the November Ly alpha profile is substantially narrower and the Ly alpha to C IV intensity ratio is reduced by roughly a factor of 2. In our February, 1981 image, the C IV profile is narrowed by approximately a factor of 2 compared with the other two observations, while the Ly alpha profile and Ly alpha to C IV ratio is essentially the same as in November. Also a short-wavelength image of the very bright Seyfert galaxy Fairall 9 were obtained an it was found that the C IV and Ly alpha lines in this object have essentially identical profiles.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 170-176
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  • 177
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    Markarian 36: A young galaxy (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The UV, optical, and IR observations of three galaxies (NGC 4214, NGC4670 = Haro 9, and Markarian 36) are reported. The optical spectrum of Markarian 36, a dwarf galaxy, is dominated by strong emission lines. The UV spectrum however shows no strong emission lines, only weak C IV and Si absorption and a strong blue continuum that is still rising shortward of Lyman alpha. Combined UV, optical and IR observations show that the continuum is nearly Rayleigh-Jeans from 1100 A to 2.2 microns, with a slight excess in the optical due to free-free emission and recombination lines. This galaxy has few, if any, red stars. Combined with its low metal content, this lack of red stars is a very strong indication that this galaxy has only recently begun to form stars.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 151-155
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  • 178
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    The impact of IUE observations on our knowledge about galaxies and quasars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Observations of extragalactic objects with IUE are discussed. Elliptical galaxies show the presence of very hot stars which are probably highly evolved horizontal branch objects, although the observations are not adequate to rule out young OB stars. Spiral and irregular galaxies often show evidence of young OB stars although the nucleus of M31 is very similar to elliptical galaxies. Several narrow emission line galaxies appear to have nonthermal continua. Observations of Seyfert galaxies permit detailed studies of the continua and line ratios such as L alpha to H beta to be made. Unlike quasars, there is evidence for dust based on the 2175 A feature. The problem of understanding Seyfert galaxy spectra is no easier than that for quasars although observed variability in the broad lines may present useful clues. Observations of high redshift quasars with IUE allow spectra to be obtained down to rest wavelengths of a few hundred Angstroms and provide information about the amount of ionizing flux. Observations of low redshift quasars can be used to test whether the myriads of absorption lines seen below L alpha in high redshift quasars are indeed produced by intergalactic clouds and halos of intervening galaxies.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 46-53
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  • 179
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    A search for UV line variability in R136a (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The brightest object in the central cluster of stars in the 30 Doradus nebula is R136a. Optical imaging and ultraviolet spectroscopy show that a luminosity originates in a volume less than 0.1 pc across. A very tight cluster of approximately 30 luminous O and WR stars produces this energy. An alternative interpretation is the possibility that a single supermassive object dominates the light. The visual spectrum is classified as WN 4.5. A common characteristic of WN spectra is variability of the emission lines, especially He II lambda 4686.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 620-624
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  • 180
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    The Orion nebula star cluster (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Photography through filters which suppress nebular light reveal a clustering of faint red stars centered on the Trapezium, this evidences a distinct cluster within the larger OB1 association. Stars within about 20 ft of trapezium comprise the Orion Nebula star cluster are considered. Topics discussed re: (1) extinction by dust grains; (2) photometric peculiarities; (3) spectroscopic peculiarities; (4) young variables; (5) the distribution and motion of gas within the cluster.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 606-609
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  • 181
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    UV fluxes and effective temperatures of extreme helium stars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Low resolution IUE spectra of a complete ensemble of extreme helium stars are presented and their appearance in comparison with normal stars is discussed. Effective temperatures from these observations by means of line blanketed model atmospheres are determined. It is found that the temperatures are in accordance with earlier results from ground based observations.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 593-596
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  • 182
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    Ultraviolet photometry of A-type stars at high galactic latitudes (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Ultraviolet photometry on the International Ultraviolet Explorer (IUE) was used to study four stars located in one target of an earlier diffuse background sounding-rocket experiment. The resulting stellar correction is much smaller than that previously estimated, giving a higher diffuse background at this target. Visible photometry appears to be a better indicator of ultraviolet flux than spectral type. The discrepancy between previous predictions and the present observations is explained in terms of: (1) misclassification of two stars; (2) use of a spectral type/effective temperature calibration hotter than more recent determinations; and (3) inadequacy of the Kurucz models, in the far ultraviolet, for A-type stars.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 597-601
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  • 183
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    Ultraviolet spectra of some bright later type Be stars and A-F shell stars (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Anomalous ionization (C IV and Si IV is seen in IUE spectra of Be stars as late as B8, and occurs also in standard stars of similar spectral type. Asymmetrical lines suggesting mass loass are present in all the Be stars and several of the standard stars as well, with no obvious correlation with v sin i. Emission shoulders are present in the Mg II lines of two B5e stars but not in Be stars of later type. No correlation is found with v sin i. The A-F shell stars show rich Fe iI absorption spectra in the ultraviolet, in one case with velocity structure.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 579-583
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  • 184
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    The X-ray binary, UW CMa (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The UW CMa is a close, eclipsing binary composed of an O7f primary with a stron wind and a less luminous O-type companion. It was found that UW CMa a variable X-ray source, whose X-ray variations are in phase with its optical light curve. Since both components of the binary system are O stars, accretion by a compact object is ruled out as a mechanism for generating X-rays. The UW CMa represents a new class of X-ray binaries, in which X-rays result from the collision of a wind from one star with the surface or wind of the other star. It is hypothesised that the impact of a wind against a star generates a shock wave about 0.25 stellar radii above the stellar surface, and material behind the shock front, heated to bout 10 million degrees, radiates the X-ray apparent X-ray variability is due to its location between the two stars, where it undergoes eclipses. The high temperature region maintains an ionization cavity in the wind, as detected with IUE. The ionization cavity is the source of depletion of absorbing ions in the wind between the two stars.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 562-565
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  • 185
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    The hot components of hydrogen deficient binaries (1982)
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    Publication Date: 2011-08-18
    Description: Low resolution IUE observations of the hot components of three very similar but peculiar objects: LSS 4300, Upsilon Sgr, and KS Per were compared. The possible evolutionary scenarios from observations and the extremely low hydrogen contents of the visible stars are discussed. It is suggested that the hot secondaries in hydrogen deficient binaries should also be hydrogen deficient.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 546-549
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  • 186
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    Results of the IUE program of monitoring the ultraviolet emission line fluxes of four binary systems: HR 1099, 2 Peg, AR Lac and By Dra (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A program to obtain IUE spectra and optical photometry and spectra of three RS CVn-type binaries (HR 1099, II Peg, and AR Lac) and the prototype BY Dra system is reported. The systems were monitored for at least one orbital phase, and periodic variations in emission line flux from II Peg and HR 1099, indicative of notational modulation of an active region on these stars were detected. It is found that for II Peg the active region is in phase with photometric minimum as expected, but for HR 1099 ultraviolet emission maximum occurs at the time of photometric maximum.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 554-557
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  • 187
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    The W Serpentis binaries with a few words on epsilon Aurigae (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Algol systems, U-Cephei and V356 Sagittarii, which should be included among the W Serpentis stars, characterized by strong ultraviolet emission lines are discussed. The spectra of the W-Ser stars are similar to those of the T-Tauri stars, and a similarity of physical conditions is indicated. A model of W-Serpentis, a B-star embedded in a thick disk, may be relevant to other exotic eclipsing systems, possibly even to obliquity of ecliptic Aurigae. The obliquity of ecliptic and the relationship to Aur, BM Orionis is reviewed; the system probably contains a pre main sequence star highly flattened by differential rotation.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 526-529
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  • 188
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    CI Cygni since the 1980 eclipse (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: During the 1980 eclipse of the 855 day period symbiotic binary CI Cyg, a data set showing high excitation resonance lines which were largely uneclipsed but brightening on an orbital timescale, and intercombination lines exhibiting pronounced but nontotal eclipses and which were fading on an orbital timescale were obtained. A model invoking a low density dissipating nebula surrounding the hot companion to explain the intercombination lines, and a shock between stellar winds to interpret the resonance lines, is described. Subsequent synoptic observations revealed continuing changes in the UV emission line fluxes consistent with those described above, except for the brightening of Mg II and the emergence of strong, not previously seen Mg V emission. Post-outburst and phase dependent changes must be included in any interpretation of this system as the archetypal symbiotic binary. Observations to be made during the 1982 October eclipse are summarized.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 509-512
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  • 189
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    Analysis of non-interacting binaries with luminous cool primaries (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High dispersion long wave redundant (LWR) spectra are analyzed for the differential velocity between hot and cool components of heretofore single lined spectroscopic binaries with late type giant or supergiant primaries. Cross correlation of a composite spectrum against early and late type standard stars yields relative velocities with an accuracy of 0.2 to 0.3 kms. When the orbit of the primay is known, the differential measurement from IUE gives the mass ratio of the system. Low dispersion short wave prime (SWP) and LWR flux spectra are used together with ground-based photometry to disentangle the composite energy distributions of the binaries. Temperatures of both components, their relative luminosities, and the reddening of the system are obtained. Assuming the hot secondaries to be main sequence stars, their probable luminosities and masses may be obtained from their temperatures. Then absolute magnitudes and masses may be obtained for the evolved primaries with more confidence than with existing techniques.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 501-504
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  • 190
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    A model for the 1979 outburst of the recurrent nova U Scorpii (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A series of ultraviolet spectra were obtained of the recurrent nova U Sco during its recent outburst with the IUE satellite. These spectra were analyzed and found to consist primarily of emission lines although broad resonance absorption is present during the first week. These data, in combination with the optical data, show that the nova ejecta is very depleted in hydrogen relative to helium and is rich in nitrogen. An optical spectrum, obtained nine months after the outburst, shows predominantly He II emission lines, indicating that the gas being transferred from the secondary is very helium rich and that the secondary is highly evolved. These data are interpreted to imply that the outburst is associated with the accretion of helium rich material by a massive white dwarf in a close binary system. Neither the observational data nor the theoretical calculations, permit differentiation between a thermonuclear runway or an accretion event as the cause of the outburst. In both cases, an equal amount of material is ejected at equal speeds.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 470-473
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  • 191
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    Data obtained from spacecraft (1982)
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    Publication Date: 2011-08-18
    Description: Data from spacecraft observations of B stars in the ultraviolet and X-ray spectral regions are presented. Superionization, mass flux, and the extended envelope are discussed in reference to ultraviolet line spectral. The problem of determining the ultraviolet flux of the B stars is examined. Spectral variations of gamma Cas and 59 Cyg are also discussed.
    Keywords: ASTRONOMY
    Type: B Stars With and Without Emission Lines, Parts 1 and 2; p 375-407
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  • 192
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    Special types of B stars (1982)
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    Publication Date: 2011-08-18
    Description: The properties of the Beta Cephei stars are examined with emphasis on spectral types, luminosities, periods, and light and velocity variations. Typical members of the group and their position in the observational and theoretical HR diagram are discussed. Those B stars with anomalous spectra (chemically peculiar) are considered including hot subdwarfs, extreme helium, weak helium, strong helium, helium variable, magnetic and mercury-manganese stars.
    Keywords: ASTROPHYSICS
    Type: NASA, Washington B Stars With and Without Emission Lines, Parts 1 and 2; p 147-163
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  • 193
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    UV emission from he M1 supergiant TV Gem (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Low and high dispersion ultraviolet spectra were obtained of the M1 supergiant TV Gem with IUE. Previous IUE observations of this late type supergiant revealed unexpected UV continuum emission, perhaps arising from an early B companion. Low resolution spectra obtained approximately one year apart suggest that the strong Si III in combination perhaps with O I at wavelengths approximately 1300 A varies considerably with time. Large variation in the column density is required to explain these changes. Sporadic mass expulsion with mass loss rates dM/dt approximately 0.00001 solar mass yr minus 1st power from the M supergiant could lead to a dense circumstellar wind near the hot early companion, and thus could account for these observed variations in equivalent width. The high resolution spectrum in the 2000 to 3200 A wavelength range is characterized by narrow absorption lines primarily due to Fe II, Mn II and Mg II (h and k), which are skewed in profile with an extended red wing. This profile structure is tentatively attributed to interstellar absorption and an intervening differentially moving cloud in the direction of Gem OB1, of which TV Gem is a known association member.
    Keywords: ASTRONOMY
    Type: Advan. in Ultraviolet Astron.; p 263-267
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  • 194
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    Chromospheric, transition layer and X-ray emission for stars with different rotational velocities (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: In agreement with previous findings for the MgII k line emission in F stars an increase of Lya and transition layer emission with increasing V sub r sin i, if v sub r sin i greater than 30 km/sec. was not found. For V sub r sin i 30 km/sec., the measured line intensities are consistent with an increase in emission with increasing V sub r sin i. Such a relation between emission and rotation for single stars is also in agreement with X-ray observations. For the young F stars in the Hyades we find generally enhanced emission independently of rotational velocities. The enhancement is most pronounced for low excitation lines.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 247-250
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  • 195
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    Chromospheric, transition layer and coronal emission of metal deficient stars (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is shown that while MgII k line emission decreases for metal deficient stars, the Ly alpha emission increases. The sum of chromospheric hydrogen and metallic emission appears to be independent of metal abundances. The total chromospheric energy loss is estimated to be 0.0004 F sub bol. The chromospheric energy input does not seem to decrease for increasing age. The transition layer emission is reduced for metal deficient stars, but it is not known whether the reduction is larger than can be explained by curve of growth effects only. Coronal X-ray emission was measured for 4 metal deficient stars. Within a 12 limit it could still be consistent with the emission of solar abundance stars.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 231-234
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  • 196
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    The ultraviolet spectrum of the high redshift BL lac object 0215+015 (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The highly variable object 0215+015 is studied. It has a range in the optical band of more than 4 magnitudes, and exhibits radidly variable polarization. At optical wavelengths it shows no emission lines but has a rich absorption spectrum with at least six, separate redshift systems. Combined are 3 LWP low-dispersion images of the object to produce a high signal-to-noise spectrum between 2400 - 3200 A which is use to study the hydrogen Lyman lines of the various redshift systems.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 193-196
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  • 197
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    Coordinated observations of Seyfert I galaxies (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A program to obtain simultaneous observations from the X-ray to the IR of Seyfert I galaxies is outlines. Of particular interest is the variability of these Seyfert nuclei. The continuum flux distribution in the UV for AkN 120 and ESO 113-IG45 (F-9) is examined.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 165-168
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  • 198
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    IUE and Einstein observations of NGC5204 (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The use of both the Einstein and IUE observations of NGC5204 to test some of the hypotheses put forward as a result of an X-ray survey of blue peculiar late type galaxies is discussed. In particular the hypothesis that binary X-ray sources of Pop I progenitors are responsible for most of the X-ray emission, is strengthened by the IUE short wavelength spectrum of NGC5204. This spectrum suggests a number of OB stars in agreement with the inferred from the X-ray luminosity. It also shows an ultraviolet excess in agreement with the large X-ray to blue flux ratio.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 145-150
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  • 199
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    The distribution of interstellar gas within 50pc of the Sun (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Previous Copernicus determinations of H I column densities in nearby stars are reviewed. These results are compared with recent ultraviolet (IUE) data and data acquired at other wavelengths. From this combined data set a coherent picture for the distribution of neutral hydrogen within 50pc of the Sun emerges. For directions away from the galactic center, the total H I column density for a 50pc line of sight is typically approximately 10 to the 18th power/sq cm, while toward the galactic center it may be 1 to 2 x 10 to the 19th power/sq cm or higher. A tentative model is proposed which suggests that the bulk of the H I resides in a cloud in a direction toward L(II) approximately 0 deg. The data are consistent with the Sun being embedded, but near the edge of the cloud.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 125-133
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  • 200
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    IUE spectroscopic investigation of interacting binary systems (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The IUE observations of binaries consisting of at least one early type star, to the Algol systems, and to W Serpentis systems are discussed. The OB close binaries almost invaribly show a stellar wind. The difference between an unevolved early type system and a slightly evolved system is difficult to discern observationally and probably not meaningful in terms of Roche lobes. the zeta Aur stars show complex gas motions and shocks. Many of the Algol systems show peculiarities in their ultraviolet continua and the resonance lines, particularly Si IV, are of abnormal and variable strength. Emission lines were detected in several systems during the total eclipse. The W Ser stars are characterized by numerous strong emission lines in their ultraviolet spectra. It appears that these systems may be related to beta Lyrae as they seem to be in a phase of rapid mass transfer and their spectra show similarities to that of beta Lyrae.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 102-113
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