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The ultraviolet variability of Seyfert 1 galaxies.
Huchra, J. P.; Geller, M. J.; Chapman, G. N. F.
Multiple IUE spectra of nine Seyfert 1 galaxies, obtained over four years, were examined. Spectra of Mrk 509, ESO 141-G55, Fairall 9, III Zwicky 2, Mrk 279, NGC 3783, NGC 4593, NGC 7213, and NGC 7469 were examined for evidence of variability in both continuum and emission-line fluxes. All except NGC 7213 and III Zw 2 show 20 percent-80 percent con…
AY Ceti : a flaring, spotted star with a hot companion.
Simon, T.; Gibson, D. M.; Fekel, F. C., Jr.
AY Ceti is a late-type single-line spectroscopic binary, a bright X-ray source (L/x/ equal to about 1.5 x 10 to the 31st ergs/s), and a spotted star, as evidenced by its prominent photometric wave. In this paper, observations made with the IUE satellite and the VLA radio interferometer are reported. The 1200-2000 A UV spectrum of AY Cet shows a ho…
The development of the new Be phase of 59 CYG in the visual and in the far UV in 1978-1983.
Bolton, C. T.; Grady, C. A.; Stalio, R. +10 more
A tentative synthesis of visual and IUE observations of 59 Cyg during 1978-1983 when the new Be phase began to develop is presented. The study reveals correlation between those spectral features originating in the cool H-alpha-emitting envelope and features originating in superionized regions exhibiting C IV and N V lines. The long-term variabilit…
Transient quasi-periodic oscillations in in the X-ray flux of Cygnus X-3
van der Klis, M.; Jansen, F. A.
Cygnus X-3, a bright X-ray source at a distance1 of more than ~12 kpc beyond the edge of the galactic plane, has peculiar properties including very strong radio outbursts2, possibly showing jet-like features3, and emission in various γ-ray bands4-6 (but see ref. 7). The discovery of its 4.8-h X-ray perio…
The structure of Herbig-Haro object 43 and Orion dark cloud extinction.
Cohen, M.; Dopita, M. A.; Schwartz, R. D.
New ultraviolet and optical observations of Herbig-Haro object No. 43 are reported. Continuum and emission-line fluxes in the wavelength range 1250 to 7350 A have been measured. The continuum fluxes are best matched by an enhanced H exp 0 two-photon component added to H free-bound emission, assuming a Theta Ori extinction curve with E(B - V) = 0.2…
Observations of the low-redshift broad absorption line QSO PG 1700+518 : limits on the fraction of QSOs with broad absorption lines at low redshift and the physical conditions in the broad absorption line region.
Peterson, B. M.; McMahon, R. G.; Weymann, R. J. +3 more
The authors present IUE and optical observations demonstrating that the zem = 0.29 QSO PG 1700+518 is a broad absorption line (BAL) QSO. This object is unique because of its low redshift and because it is one of only two BAL QSOs which exhibit moderate strength Mg II BALs. The discovery suggests that the fraction of QSOs with BALs at lo…
Models for the planetary nebulae NGC 4361 and NGC 1535 : influence ofthe stellar wind on the nebular ionization.
Koeppen, J.; Adam, J.
Model atmospheres fitted to line profiles of the central stars (Méndez et al., 1981) are used to construct nebular ionization models for the planetary nebulae NGC 4361 and 1535. For NGC 4361 the optical and IUE nebular emission lines are reproduced satisfactorily well. For NGC 1535 the model atmospheres only emit less than 10-3 of the n…
The old nova V603 AQL : an intermediate polar ?
Haefner, R.; Metz, K.
A total of 1510 UVB photometric observations obtained with the 50-cm telescope at ESO in 13 6-h runs during July-August 1981 and two-channel polarimeter measurements obtained at the 60-cm Bochum and 1-m telescopes at ESO during the same period are reported for the old nova V 603 Aql. The data are presented in graphs and tables and characterized in…
PG 1700+518 : a low-redshift, broad absorption line QSO.
Boksenberg, A.; Pettini, M.
The first high-resolution optical spectra and lower resolution UV spectra of PG 1700 + 518, the only known broad-absorption-line (BAL) QSO at low emission redshift (0.288) are presented. The optical data were obtained with the Isaac Newton Telescope on the island of La Palma and the UV data with the International Ultraviolet Explorer satellite. Th…
Ultraviolet spectral morphology of the O stars. III. The ON and OC stars.
Walborn, N. R.; Panek, R. J.
Key regions in the 1200-1900-A spectra of two ON dwarfs and four ON/OC supergiants are illustrated and discussed, using high-resolution data from the International Ultraviolet Explorer archives. Marked anomalies are displayed by both stellar wind and photospheric C and N features, relative to the consistent framework provided by normal ultraviolet…