Search Publications
The X-ray modulation of CYG X-3.
van der Klis, M.; Bonnet-Bidaud, J. M.
Results of three 40d COS-B X-rays observations of Cyg X-3 are presented. The shape of the light curve, although variable from cycle to cycle, is generally very stable when averaged over many cycles. During one four-week period, however, a different mean light curve was observed. It is shown that the correlated behavior of amplitude, average level,…
Long term X-ray observations of SMC X-1 including a turn-on.
van der Klis, M.; Bonnet-Bidaud, J. M.
A 38 d COS-B observation of SMC X-1 in the 2-12 keV band is presented, the observation including a turn-on of this source. The data are analyzed within the framework of the stellar wind accretion model, both from the point of view of the expected accretion rate and of the absorption of X-rays in the wind. It is noted that neither the high state lu…
Variability of the continuum and the emission lines in the Seyfert 1 galaxy Akn 120.
Kollatschny, W.; Yorke, H. W.; Fricke, K. J. +1 more
Far UV study on the non-thermal activity in the narrow line galaxies NGC 4507 and NGC 5506.
Maccacaro, T.; Bergeron, J.; Perola, C.
The narrow line high excitation galaxies NGC 4507 and NGC 5506 were observed with IUE satellite in the low resolution mode. The continua of both galaxies, when combined with optical observations, show a flattening at log nu greater than 14.9. The reddening correction cannot be estimated with accuracy. The energy content in the Lyman continuum is l…
Photometric orbit of the massive system RY Sct.
Strazzulla, G.; Milano, L.; Vittone, A. +3 more
The UBV lightcurves of RY Scuti were analyzed using the Wilson and Devinney approach (1971). The system is found to be an evolved overcontact system, embedded in a gas and dust envelope, revealed by forbidden lines and IR excess. It is suggested that RY Scuti has early-type components of 39 and 49 solar masses, making it one of the most massive co…
The ultraviolet spectrum of the normal giant elliptical NGC 4472.
Norgaard-Nielsen, H. U.; Kjaergaard, P.
Low resolution IUE spectra of NGC 4472 covering the wavelength region 1100-3300 Å have been obtained. Strong emission lines have probably been found in the short wavelength region. Such emission lines have also been found in M 31, M 32, and in the nucleus of M 87. Most of the lines can be identified with known chromospheric lines, the relative str…
The planetary nebula NGC 7009.
Perinotto, M.; Benvenuti, P.
IUE observations of the planetary nebula NGC 7009 and its central star are presented and used to derive the physical properties of the system. Low-resolution spectra were obtained by the SWP and LWR cameras using the large aperture centered on the nucleus and 6.5 arcsec NE of it. When combined with optical line ratios, the UV data indicate an elec…
TT Ari : a new dwarf nova.
Vogt, N.; Wolf, B.; Drechsel, H. +4 more
The novalike variable TT Ari was observed during the recent remarkable minimum with the IUE on November 17 and 23, 1980, in the low resolution mode in the 1200-3200 A region. The spectrum is characterized by prominent resonance emission lines. A comparison of this spectrum with the spectrum of TT Ari at maximum and with the spectra of dwarf novae …
The ultraviolet spectrum of the planetary nebula NGC 2371 and its exciting star.
Pottasch, S. R.; Wesselius, P. R.; Gilra, D. P. +1 more
Low resolution IUE spectra have been taken of the planetary nebula NGC 2371. Some were centered on the exciting star while other spectra measure only nebula emission. We discuss the nebula line and continuum spectrum in terms of the physical state of the nebula gas and its abundance. The stellar spectrum yields information on the atmospheric tempe…
Discovery of strong ultraviolet absorption in the spectrum of the DC white dwarf G 33-49.
Koester, D.; Weidemann, V.; Vauclair, G.
Strong ultraviolet absorption features have been observed by IUE in the spectrum of the DC white dwarf G33-49. The spectrum between 1400 Å and 106 Å is quite to the one obtained for the C2 weak white dwarf L145-141, and shows strong absorptions at (FWHM 70 Å) and between 1550 Å and 1680 Å. Identification with carbon absorption features is discusse…