Search Publications
Periodicity Search in Sources with Low Count Rate
Bisnovatyi-Kogan, G. S.; Gurin, L. S.; Beliaeva, N. P. +2 more
The problem of discovery and estimation of the period, slowly changing in time is considered, when the pulses are rare. Several criteria are proposed on the base of which a multilevel algorithm of the period detection is constructed. The reliability and precision of the period determination are investigated with taking into account of the correlat…
Column Densities of Interstellar Matter in the Direction of the Star Kappa-Cassiopeiae B1IA
Mentese, H. Huseyin
We have studied the interstellar column densities in the direction of the star κCas with the IUE high resolution SWP spectrum so as to see the relations of element depletions with condensation temperature and compare our results with the interstellar column densities in the directions of the other B-type stars obtained with the COPERNICUS satellit…
Multi-frequency observations of the 1985 outburst of RS ophiuchi
Snijders, M. A. J.
The 1985 outburst of the bright, recurrent nova RS Oph was almost simultaneously observed at X-ray, UV, optical, IR and radio frequencies at many epochs. The abundances in the ejected shell and the development of the bolometric luminosity as a function of time suggest that the cause of the outburst is a nuclear runaway on a massive white dwarf.
New EXOSAT Observations of Tv-Columbae - Preliminary Results
van der Woerd, H.; Brinkman, A. C.; Schrijver, J.
The first results of the analysis of new EXOSAT observations of the DQ Her type cataclysmic variable TV Col are presented. The period of the 1–10 keV X-ray pulsation associated with the white-dwarf rotation is now established as 1911 s. The pulsations are most pronounced in the lower energy channels (1–3.5 keV). The X-ray light curve shows absorpt…
Periodic Variabilities in the IUE Spectra of Ss-Cygni
Gaudenzi, S.; Giovannelli, F.; Lombardi, R.
The analysis of the IUE low resolution spectra of SS Cyg in quiescence clearly shows modulations with the orbital phase of the continuum and the emission lines total area. The shape of such modulations is depending on the type of the optical outburst preceding the quiescent phase in which the UV spectra were collected. This behaviour, together wit…
EXOSAT Observations of H2252-035 - Pulse Phase and Orbital Phase Dependent Low Energy Absorption and Iron Line Emission
Pietsch, W.; Pakull, M.; Kendziorra, E. +1 more
The 805 sec pulsing X-ray source H2252-035 has been observed for 7 h on September 14/15 and on September 17, 1983 in X-rays with the low energy telescope and the medium energy detectors of EXOSAT. While below 2 keV the semiamplitude of the 805 s pulses is ∼100% in the 2.3–7.9 keV band it is only ∼40%. X-ray dips that are more pronounced in low ene…
EXOSAT observations of the ring nebula NGC 6888 and HD 192163
Kaehler, H.; Ule, T.; Wendker, H. J.
A 25 hr exposure of the ring nebula NGC 6888 was obtained with the EXOSAT X-ray Observatory. X-ray emission of the nebula was not found. Taking all instrumental effects and the large nebular area into account, a conservative upper limit of 1×10‑12 erg s‑1 cm‑2 (0.05–2 keV) is derived. This is about an order of magn…
Changes in the Soft and Hard X-Ray Lightcurves of the Am-Herculis Object E:1405-451
Cristiani, S.; Cropper, M.; Osborne, J. P.
The preliminary results of EXOSAT and contemporaneous optical observations of E1405-451 (V834 Cen) in 1985 and 1986 are presented. In the latter of the two observations the soft X-ray light curve was observed to be quite different to that seen in all previous observations, but similar to the optical light curve and the new soft X-ray light curve o…
IUE observations of CH Cygni continuum during 1979–1986
Hack, M.; Mikolajewska, J.; Selvelli, P. L.
Variations of the UV continuum have been analyzed. The observed UV continuum may be reproduced by a superposition of a Kurucz model atmosphere (log g=2), Teff∼8500–15000 K) and optically thin hydrogen bound-free and free-free emission (Te∼ 1000 K). The temperature of the Kurucz atmosphere is the lowest at the maximum of brigh…
Continuum Distributions and Line Profiles of Ux-Ursae Type Nova like Systems
Haug, K.
Combined UV, optical and, in part, IR continuum distributions of the UX UMa-systems CPD-48°1577, V3885 Sgr, RW Sex and of the recently discovered cataclysmic system PHL 227 were determined from multi-wavelength spectroscopic and photometric data to search for general characteristics of these systems. The observed variations of the UV to IR spectro…