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Highly ionized species in the spectra of Small Magellanic Cloud stars
Ferlet, R.; Vidal-Madjar, A.; Lequeux, J. +7 more
Preliminary results of high-resolution IUE observations of the star Sk 159 in the Small Magellanic Cloud (SMC), and of low-resolution observations of this star and of six other SMC stars are presented. A study of C IV and Si IV circumstellar absorption suggests a stellar mass loss rate smaller than in the Galaxy and the large Magellanic Cloud. Int…
Astrophysical interpretation of the lam lam 1200-7300 angstrom emission line spectrum of a filament in the CYG Loop Supernova remnant.
Dennefeld, M.; Benvenuti, P.; Dopita, M. A. +2 more
An IUE spectrum of a filament in the Cygnus Loop supernova remnant obtained with the low resolution, long wavelength camera, has been combined with earlier far UV and optical data to obtain a complete spectral coverage between 1200 and 7350 Å. The observed continuum is fully understood as a combination of free-free emission, recombination and hydr…
International Ultraviolet Explorer Satellite Observations of Seven High-Excitation Planetary Nebulae
Keyes, C. D.; Aller, L. H.
Observations of seven high-excitation planetary nebulae secured with the International Ultraviolet Explorer (IUE) satellite were combined with extensive ground-based data to obtain electron densities, gas kinetic temperatures, and ionic concentrations. We then employed a network of theoretical model nebulae to estimate the factors by which observe…
Presidential address : spectra of gaseous nebulae.
Seaton, M. J.
A brief historical review of observations of planetary nebulae are presented with attention given to Herschel's observation of NGC 1514 (1790) and Huggins' observations (1864). The current status of observations of gaseous nebulae is also presented; consideration is given to the identification of nebular lines, physical processes, the radio contin…
Electron densities for six planetary nebulae and HM SGE derived fromthe CIII lambda 1907/1909 ratio.
Feibelman, W. A.; Hobbs, R. W.; Boggess, A. +1 more
Electron densities for IC 418, NGC 6572, IC 1297, NGC 3242, NGC 6818, NYC 3211, and HM Sagittae derived from high-dispersion IUE C III] spectrograms are consistently higher than those derived from either surface brightness measurements or forbidden line intensity ratios in the visible. The nebulae were selected for a range of excitation classes fr…
Ultraviolet, optical, and infrared observations of the Herbig Be star HD 200775.
Altamore, A.; Baratta, G. B.; Viotti, R. +3 more
The Herbig Be star HD 200775, associated with the extended reflection nebulae NGC 7023, has been observed in the ultraviolet with the IUE satellite, in the optical with the 90-cm Schmidt telescope of Campo Imperatore Observatory, and in the infrared with the 2.3 m telescope of Wyoming University in a coordinated campaign made during August 1978. T…
Ultraviolet, visual, and infrared observations of the peculiar Be star HD 45677.
Savage, B. D.; Sitko, M. L.
The peculiar Be star HD 45677 was observed at low and high resolution by the IUE, and nearly simultaneous optical and IR observations were obtained with ground-based telescopes. These data were used to produce a spectral energy distribution extending from 0.12 to 12.6 microns in order to investigate the conversion of UV to IR radiation in the circ…
Far UV observations of PKS2155-304
Maraschi, L.; Tanzi, E. G.; Tarenghi, M. +1 more
In BL Lac objects the absence of broad emission lines may be due either to a lack of ionizing continuum or to a lack of cool gas (T <~ 104K)1. UV observations of BL Lac objects are interesting in that they provide a measurement of the continuum, and they include the wavelength range of Lyα, which is in principle the most f…
The detection of a companion star to the Cepheid variable T Monocerotis
Doschek, G. A.; Mariska, J. T.; Feldman, U.
We have obtained ultraviolet spectra with the International Ultraviolet Explorer (IUE) spacecraft of the classical Cepheid T Mon at several phases in the 27 day period. Significant ultraviolet emission is detected at wavelengths less than 1600 A, where little flux is expected from classical Cepheids. Furthermore, the emission at wavelengths less t…
Spectral evolution of nova CYG 1978.
Wolff, B.; Krautter, J.; Klare, G.
The evolution of the spectrum of Nova Cygni 1978 from the principal to the nebular stages is investigated. Spectrograms were obtained in the blue (between 3900 and 5100 A) and red (5600-6840 A) between September 13 and December 18, 1978. The principal spectrum of the nova, taken around maximum light on September 13, is found to be characterized by…