Search Publications
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…
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 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…
Discrete sources of cosmic gamma rays
Wolfendale, A. W.; Li, T. P.
The possibility is considered that some unidentified gamma-ray sources are in fact not discrete sources but rather 'apparent sources' caused by cosmic-ray irradiation of the clumpy interstellar medium. It is shown that six of nine unidentified gamma-ray sources in the 2CG catalog can be explained in terms of the mechanism considered and that the s…
IUE observations of UV absorption in the spectrum of the C2 white dwarf L 1363-3.
Koester, D.; Weidemann, V.; Vauclair, G.
Strong ultraviolet absorption features have been observed in a short wavelength IUE spectrum of the weak carbon white dwarf L1363-3. The spectrum is quite similar to those obtained for the weak C2 white dwarf L145-141 and the DC white dwarf G33-49 and shows strong absorption at 1920 A and between 1520 A and 1680A. Identification with carbon absorp…
IUE observations of quasars 3C 249.1 and 3C 232
Dultzin-Hacyan, D.; Daltabuit, E.; Salas, L.
Spectra of quasars 3C 249.1 and 3C 232 (TON 469) were obtained with the International Ultraviolet Explorer Satellite. In 3C 232 the Lyman series is observed up to Lyman delta and two hydrogen ionizing lines shortward of Lyman delta are observed. The possibility of identifying weak Fe II features is pointed out. Emissions at 1116, 1146, 1166, and 1…
The graphite rich Cepheus OB3 association.
Panagia, N.; Perinotto, M.; Barsella, B.
The four optically brightest stars of the Cepheus OB 3 association have been observed with the IUE satellite in the spectral range 1150-3200 A. The extinction suffered by the stars has been investigated. Both the shape of the bump at approximately 2200 A and the behavior of the extinction at longer wavelengths are close to those of the mean inters…