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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…
IUE observations of UV carbon I absorption lines in the spectrum of the C2 white dwarf L 97-3.
Koester, D.; Weidemann, V.; Vauclair, G.
Extremely strong absorption features have been detected in the short wavelength UV spectrum of a cool helium-rich white dwarf, L 97-3, classified C2 weak from faint Swan band absorption in the visible. The spectrum shows the signature of neutral carbon, whose resonance lines as well as at least 4 additional lines are identified. The car…
Electron densities for 10 planetary nebulae derived from the CIII 1907/1909 ratio. II.
Feibelman, W. A.; Hobbs, R. W.; Boggess, A. +1 more
Electron densities for IC 351, IC 2165, J900, IC 3568, NGC 6644, NGC 6891, IC 4997, NGC 7009, Hu 1-2, and IC 5217 are derived from high-dispersion semiforbidden C III spectrograms. For seven of these nebulae, the derived electron density is larger than the values derived from either surface brightness measurements or forbidden line ratios. Only on…
A remarkable H-alpha outburst in the RS CVn binary SZ PISCIUM - A transient mass-transfer event
Bopp, B. W.
The very unusual spectroscopic behavior of the RS CVn binary SZ Psc (K1IV + F8V; P = 3.97 days) is described. For much of the time the Ha line in the K star appears as a weak absorption feature, presumably partially filled by chromospheric emission. The Hα equivalent width ordinarily shows small variations that may be adequately explained by stell…