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The planetary nebula NGC 7009.
Perinotto, M.; Benvenuti, P.
IUE observations of the planetary nebula NGC 7009 and its central star are presented and used to derive the physical properties of the system. Low-resolution spectra were obtained by the SWP and LWR cameras using the large aperture centered on the nucleus and 6.5 arcsec NE of it. When combined with optical line ratios, the UV data indicate an elec…
On the nebulosities associated with the extreme of star HD 148937.
Gull, T. R.; Bruhweiler, F. C.; Henize, K. G. +1 more
In order to understand the origin of the extreme Of star HD 148937, a study was undertaken of the interrelations between (1) its associated nebulae, including NGC 6164-5, (2) a 2 deg diameter H II region, (3) an outer dust shell, and (4) a newly identified interstellar bubble. A self-consistent model describing the interaction of HD 148937 with th…
TT Ari : a new dwarf nova.
Vogt, N.; Wolf, B.; Drechsel, H. +4 more
The novalike variable TT Ari was observed during the recent remarkable minimum with the IUE on November 17 and 23, 1980, in the low resolution mode in the 1200-3200 A region. The spectrum is characterized by prominent resonance emission lines. A comparison of this spectrum with the spectrum of TT Ari at maximum and with the spectra of dwarf novae …
The ultraviolet spectrum of the planetary nebula NGC 2371 and its exciting star.
Pottasch, S. R.; Wesselius, P. R.; Gilra, D. P. +1 more
Low resolution IUE spectra have been taken of the planetary nebula NGC 2371. Some were centered on the exciting star while other spectra measure only nebula emission. We discuss the nebula line and continuum spectrum in terms of the physical state of the nebula gas and its abundance. The stellar spectrum yields information on the atmospheric tempe…
Observation by COS-B of the gamma-ray source 2CG195/plus/04
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +7 more
Data accumulated from observations of the high-energy gamma-ray source 2CG195(plus)04 are used to improve the position and energy spectrum of the source, and to search for short term variability. Skymaps from four observations in three energy ranges are analyzed using the cross-correlation method by Hermsen (1980), and results are within the error…
The ultraviolet spectrum of the twin-degenerate interacting binary G 61-29.
Lambert, D. L.; Slovak, M. H.
A low-resolution IUE spectrum (1200 A-1900 A) of the twin-degenerate white-dwarf binary star G61-29 is presented. A comparison is made to similar IUE spectra of the old novae DQ Her and V603 Aql. G61-29 shows N V 1240 A and He II 1640 A in emission. Unlike the old novae, the C IV 1550 A doublet is not present. It is proposed that the mass-losing H…
A classification system for O - B2 stars based on the Si IV and C IV resonance lines.
Wray, J. D.; Parsons, S. B.; Henize, K. G.
Low-dispersion ultraviolet spectra from Skylab Experiment S-019 are used to explore the variations of Si IV and C IV line strengths with temperature and luminosity. These considerations lead to a classification system in which the Si/C ratio is used to discriminate luminosity among the O stars and temperature among the O9-B2 stars of lower luminos…
Observations of strong ultraviolet absorptions in the spectrum of theDC white dwarf G 218-8.
Wegner, G.
The spectrum of the 14th magnitude DC white dwarf G218-8 (EG 245) is described. In the visible spectral region the star has been observed with the IIDS scanner attached to the Kitt Peak National Observatory 2.1 m telescope, where it shows a featureless spectrum. However, the ultraviolet observations using the IUE satellite show that strong absorpt…
Ultraviolet spectra of planetary nebulae - the C II 1335 dielectronic recombination lines in IC 418.
Clavel, J.; Seaton, M. J.; Flower, D. R.
High-dispersion observations of IC 418 by the IUE satellite show the C II lines (1) 1334.53 A, (2) 1335.66 A, and (3) 1335.71 A. The profiles are of the P Cygni type, a form expected to result from scattering in the expanding nebular shell, with a mean velocity difference between nebular emission lines and interstellar absorption lines of 47 km/se…
Discovery of strong ultraviolet absorption in the spectrum of the DC white dwarf G 33-49.
Koester, D.; Weidemann, V.; Vauclair, G.
Strong ultraviolet absorption features have been observed by IUE in the spectrum of the DC white dwarf G33-49. The spectrum between 1400 Å and 106 Å is quite to the one obtained for the C2 weak white dwarf L145-141, and shows strong absorptions at (FWHM 70 Å) and between 1550 Å and 1680 Å. Identification with carbon absorption features is discusse…