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IUE observations of the Seyfert 1.9 galaxy Markarian 423.
Rudy, R. J.; Puetter, R. C.; Cohen, R. D.
UV observations of the Seyfert 1.9 galaxy Markarian 423 show a moderately strong UV continuum in the 1200-2000 A region, a strong narrow Lyman-alpha conponent, and no detectable broad lines. This absence of broad UV lines, in conjunction with the steep broad line Balmer decrement, indicates that the gas giving rise to the broad emission lines is s…
Chromospheric activity and TiO bands in M giants.
Johnson, H. R.; Steiman-Cameron, T. Y.; Honeycutt, R. K.
Low-resolution IUE spectra of 23 cool giant stars ranging from K3 through M6 have been used to examine chromospheric activity in late-type giants. Previous studies have suggested a decrease in the fractional flux, normalized to bolometric flux, of the Mg II resonance lines (an indicator of chromospheric activity) with effective temperature. Using …
Images in the rocket ultraviolet : the initial helium abundance and distance modulus of the globular cluster M5 from photometry of horizontal-branch stars.
Bohlin, R. C.; Stecher, T. P.; Cornett, R. H. +2 more
A natural laboratory for the study of postmain-sequence evolution of low-mass (less than one solar mass) metal-poor stars is provided by globular clusters. These clusters are, therefore, a critical aid for developing an understanding of advanced stages of stellar evolution and of the chemical evolution of the Galaxy. Bohlin et al. (1983) have desc…
Outflow in the nucleus of the Seyfert I galaxy NGC 3783.
Wamsteker, W.; Barr, P.
Averaged low-resolution IUE spectra of the Seyfert I galaxy NGC 3783 at two brightness levels are presented. The wavelength interval 1250-1400 A, which is essentially free of emission lines in active galaxies, contains two absorption lines at 1303 A and 1335 A. The line at 1303 A shows, in contrast to the line at 1335 A, considerable variations wi…
IUE spectroscopy, visible-band photometry and polarimetry of HD 47732(V641 Monocerotis).
Koch, R. H.; Hrivnak, B. J.; Bradstreeet, D. H. +3 more
Several high- and low-dispersion IUE spectra are described for the hot, massive close binary HD 47732. The stellar silicon lines do not show theoretically expected strength, the weakness being attributed to incipicent emission. A weak stellar wind is measurable with an expansion velocity of about 500 km/s. There is difficulty in fitting a model at…
Ultraviolet spectra and chromospheres of R stars.
Johnson, H. R.; Eaton, J. A.; Obrien, G. T. +1 more
Long-wavelength IUE spectra of 13 normal R stars and two hydrogen-deficient R0 supergiants were obtained. Early R stars are noted to have line spectra and levels of flux in the ultraviolet characteristic of G5-K2 III stars, whereas late R stars were observed to have colors and line spectra similar to late K and M stars, but with greatly enhanced s…
Discovery of an accretion shock cone in 22 Vulpeculae.
Parsons, S. B.; Ahmad, I. A.
A previous report that 22 Vul is a zeta Aurigae-type eclipsing binary is supported by the discovery of evidence for an accretion shock cone in 22 Vul similar to those found in zeta Aurigae and 32 Cygni. Such systems consist of a cool supergiant star primary and a hot dwarf secondary (G3 Ib-II and B9 in the case of 22 Vul) and undergo atmospheric e…
Evidence for supermassive stars in three Seyfert galaxy nuclei from IUE spectra.
Stoner, R.; Ptak, R.
The variability in the ultraviolet continua and the C IV 1550 A emission profiles in the three Seyfert 1 galaxies NGC 4151, NGC 5548, and Fairall 9 are consistent with origin in supermassive stars undergoing explosive mass loss. Blackbody fits to continua of each imply a single thermal source whose area either remains constant or increases moderat…
Studies of hot B subdwarfs. II. Energy distributions of three bright sdB/sdOB stars in the 950-5500 A range.
Veilleux, S.; Fontaine, G.; Wesemael, F. +2 more
Voyager ultraviolet spectrometer observations of the subdwarf B or OB stars HD 205805, UV 1758+36 and Feige 66 are presented. All three objects display the H I Layman series in absorption. These observations are combined with low dispersion IUE spectrophotometry and with Stromgren photometry to construct virtually complete energy distributions, wh…
Dynamical activity in V1016 Cygni.
Feibelman, W. A.; Fahey, R. P.
New high-dispersion IUE observations show the C IV emission lines in V1016 Cyg to be split, suggesting evidence for dynamical activity. The [Mg V] line shows structure nearly identical to the C IV lines when plotted in velocity space.