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C IV and Lyman-alpha emission lines in Seyfert 1 galaxies
Stoner, R.; Ptak, R.; Gregory, S.
Good resolution spectra of C IV and Lyman-alpha emission in four Seyfert 1 galaxies (NGC 5548, NGC 4151, NGC 3738, and Fairall 9) are examined, reporting the line profiles and intensity information for this emission. The observations are made with the short wavelength prime camera on the IUE satellite, with a spectral coverage from 1150 A to 2000 …
Abandances in the planetary nebula NGC 6853.
Pottasch, S. R.; Wesselius, P. R.; Gilra, D. P.
IUE ultraviolet spectra have been analysed of several portions of planetary nebula NGC 6853. Combining these measurements with those made from the ground, we are able to determine the relative abundances of C, N, O, and Ne, without making any important assumption concerning the ionization of any of these elements. C, O, and Ne have solar abundance…
The X-ray flux variations of CYG X-2.
van der Klis, M.; Bonnet-Bidaud, J. M.
Results of a 47 d observation of Cygnus X-2 by the COS-B X-ray experiment are presented. The observed variability of the X-ray intensity is investigated for the presence of modulation at either the 9.843 d optical period or the 11.23 d X-ray period claimed for this source. Upper limits are given to pulse amplitudes for periods between 1 d and 200 …
The width of echelle orders in IUE images as derived with the astronomical image display and analysis /AIDA/ system in Tuebingen
de Boer, K. S.; Preussner, P. -R.; Grewing, M.
This paper describes the image display and analysis facilities developed at the Astronomical Institute in Tübingen. The software governing the system is highly modular and allows easy addition of further routines. With this system we have determined the width of the echelle orders in International Ultraviolet Explorer geometrically and photometric…
Mass loss from Be stars derived from UV spectra.
de Freitas Pacheco, J. A.
The present investigation considers the interpretation of UV line profiles of some Be stars obtained with the International Ultraviolet Explorer (IUE) spacecraft, giving particular attention to Pi Aqr. The mass-loss rates are estimated using the Sobolev approximation and assuming that the observed asymmetric UV lines are formed in an expanding env…
A brightness of the symbiotic variable SY Mus.
Feibelman, W. A.; Kafatos, M.; Michalitsianos, A. G. +1 more
The symbiotic variable SY Muscae has been observed with IUE in September 1980 and June 1981 and in the photographic region in May 1981. The entire ultraviolet spectrum brightened between September and June by about a factor of 5. The spectrum shows high excitation including emission from N v and high electron density, about 10-billion per cu cm as…
The physical state of the gas towards HD 93206.
Welsh, B. Y.; Thomas, C. K.
A description is presented of a high resolution study of the ultraviolet spectrum of the star HD 93206 using the IUE satellite. This star is among those observed at optical wavelengths by Walborn and Hesser (1975) and belongs to the Cr 228 association which lies approximately 15 arcmin south of the peculiar object of Eta Car. This star is part of …
The pulsation of the outer layers of the BET CEP star SIG Sco.
de Jager, C.; Burger, M.; van den Oord, G. H. J.
The pulsation of the outer layers of the Beta Cephei-type variable σ Sco is investigated using 17 ultraviolet spectrograms (1200-2000 A) obtained during seven hours of observations with the International Ultraviolet Explorer. A pulsational model established earlier for BW Vul is confirmed. According to this model, after a period of photospheric re…
On structure of the outer layers of the cool carbon stars.
Querci, M.; Querci, F.; Cassatella, A. +2 more
Exposures on the spectra of four late C-type stars have been made with the IUE satellite in the wavelength range of the LWR camera (1900-3200 A). Two Mira variables near maximum light and two semiregular variables were observed. Although the exposure times used, which range up to 240 min in the low-resolution mode, were more than sufficient to rec…
IUE low-dispersion spectra of six luminous stars in symmetric nebula.
Johnson, H. M.
The stars and nebulae are HD 156738 and HDE 319703A, respectively centered in a pair of symmetric nebulae among the NGC 6334 group, AG Car in its nebula, HDE 250550 in nebula 8 of a catalog by Herbig, 209 BAC in Ml-67, and HD 89358 in NGC 3199. These include two O stars, two WN stars, an unstable B supergiant, and a ZAMS B star. Four of them are a…