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The absorption near 1400 A in the spectra of additional DA white dwarfs.
Wegner, G.
Ultraviolet spectroscopic observations of five white dwarfs having published spectral types of DA made with the International Ultraviolet Explorer (IUE) satellite are reported. The three coolest objects: GD279 (0148 + 46), W485A (1327 - 08), and G231 - 40 (2117 + 53) have easily detected absorptions near lambda 1400. Of the two remaining stars, PG…
The distribution of interstellar matter toward Tycho's supernova remnant and its relation to distance estimates.
Raymond, J. C.; Black, J. H.
Observations of interstellar absorption lines in the spectra of five stars in the direction of Tycho's Supernova Remnant are presented. The profiles show significant absorption at large negative velocities, - 50 to - 60 km/s (LSR). This information, together with the distances of the background stars, permits limiting distances to be assigned to t…
NGC 3448 revisited : a combined optical, radio and UV investigation.
Casini, C.; Bertola, F.; Bettoni, D. +3 more
The present combined optical, radio, and UV observations are of the irregular galaxy NGC 3448. It interacts with a smaller spiral companion, UGC 6016, forming the peculiar system Arp 205. Rotation curves were constructed from the red lines of a KPNO spectrum and from VLA H I observations. Abnormal velocity features were detected, and are attribute…
A hot companion to MU Sagittarii : an opportunity to sound the atmosphere of a B8 IA supergiant.
Plavec, M. J.; Polidan, R. S.
It is argued that the bright supergiant star Mu Sagittarii is accompanied by a smaller and hotter star, of spectral type approximately B1.5 V. The single-line radial-velocity curve of the B8 star leads to a fairly large mass function, f(m) = 2.64 solar masses, implying that the companion should have at least 50 percent of the mass of the visible s…
E(B-V) extinction values for 24 planetary nebulae derived from IUE data.
Feibelman, W. A.
Excellent agreement was found for E(B - V) values for nine planetary nebulae observed in common by IUE and ANS, derived from a strong 2200A absorption feature. E(B - V) values for seven additional objects with moderately strong 2200A absorption were determined. A third group of eight planetary nebulae for which the 2200A absorption feature is marg…
Observations of Uranus, Neptune, and Titan by the International Ultraviolet Explorer
Owen, T.; Caldwell, J.; Butterworth, P. S. +3 more
The ultraviolet spectra of Uranus, Neptune, and Titan do not reveal absorption features at 7-A resolution from 2100 to 3200 A. Upper limits of from 1 to 3 A are set for the equivalent widths of narrow absorptions, which corresponds to a CO/H2 mixing ratio less than 2 x 10 to the -4th in the case of Uranus. The slopes of the continuum reflectivitie…
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…
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…
Molecular hydrogen ion (H2+) absorption in planetary nebulae.
Feibelman, W. A.; Hobbs, R. W.; Boggess, A. +1 more
Several IUE spectra of planetary nebulae show an absorption feature shortward of 1500 A which is believed to be due to H2(+). The nebulae are excited by stars of spectral type O3-O7 or continuum, and all but one have double-shell structure.
Interstellar abundances derived from IUE data. I. Silicon depletions toward reddened stars.
Joseph, C. L.; Snow, T. P., Jr.
Surveys of abundances for species well suited to IUE's wavelength coverage and spectral resolution are undertaken to acquire interstellar line data for a large number of stars and column densities greater than those of previous instruments. A complex set of interactive computer programs has been developed for the efficient analysis of the IUE data…