Search Publications
Spectral and correlated timing behaviour of GX5-1.
van Paradijs, J.; van der Klis, M.; Lewin, W. H. G. +4 more
We have analyzed the X-ray spectral and fast timing behaviour of the Z-source GX5-1 using X-ray colour-colour diagrams (CDs), hardness-intensity diagrams (HIDs) and power spectra. We used all EXOSAT ME data on GX5-1, a total of seven observations during 1983-1985. We detect, for the first time in GX5-1, secular motion of the well known "Z" pattern…
Photometric and spectroscopic studies of cool stars discovered in EXOSAT X-ray images II. Lithium abundances
Tagliaferri, G.; Pasquini, L.; Pallavicini, R. +2 more
We present high-resolution spectra in the Li I 6708 A region, and multicolor photometry, for a sample of active stars detected serendipitously by the EXOSAT satellite. We analyse the spectral data with a spectral synthesis code and derive Li abundances, rotation rates and metallicities. We use our multicolor photometry to infer the spectral classi…
ROSAT X-ray observations of ten cataclysmic variables.
Verbunt, Frank; van Teeseling, Andre
Ten cataclysmic variables have been observed with the ROSAT PSPC. The x-ray spectra can be fitted with optically thin spectra, but several spectra require more than one component. The high emission measures indicate that the emitting plasma is optically thick in strong resonance lines. Variability in the count rate is discovered in seven systems; …
X-ray irradiation of white dwarf atmospehres : the soft X-ray spectrum of AM Herculis.
Paerels, Frits; van Teeseling, Andre; Heise, John
We present model atmosphere calculations of white dwarfs irradiated at the surface by hard x-rays. We use a self-consistent treatment of Compton scattering as a noncoherent scattering process. The opacities include the photoionization edges of all individual subshells of the most abundant ions of 15 elements. Because of an 'inverse' blanketing eff…
High time resolution observations of Cygnus X-3 with EXOSAT.
van der Klis, M.; Berger, M.
We have studied the fast timing behaviour of Cygnus X-3 using the entire EXOSAT ME dataset on this source, consisting of 22 observations that cover a total of 320000seconds. This large amount of data allowed us to measure the rapid (>1Hz) X-ray variability of the source to an unprecedented accuracy of 0.2% fractional rms amplitude. Above 256Hz,…
X-ray spectra of a complete sample of extragalactic core-dominated radio sources.
Worrall, D. M.; Brunner, H.; Staubert, R. +1 more
We present ROSAT soft X-ray spectra for the members of a complete sample of 13 core-dominated, flat radio spectrum sources. The sample comprises all radio sources from a flux-limited radio catalog (S_5 GHz_ > 1 Jy; Kuehr et al.) which are north of δ= 70deg, at galactic latitudes b > 10deg, and have a flat radio spectrum between 1.4 and 5 GHz…
Analysis of ROSAT pointed observations of 15 hot DA white dwarfs.
Wolff, B.; Jordan, S.; Koester, D. +1 more
We present the results of pointed observations of hot white dwarfs with the ROSAT PSPC detector, and through the P1 filter of the Wide Field Camera. Model atmospheres containing hydrogen and helium, either homogeneously mixed or chemically stratified, are used to analyze the new data together with observations of the same objects by EXOSAT and the…
The EUV spectrum of AU Microscopii: temperature and density diagnostic from EUVE Spectrometers observations.
Landini, M.; Monsignori Fossi, B. C.
EXOSAT and IUE observations of the active star AU Mic are used to develop a model of the differential emission measure distribution (DEM) versus temperature. The signals detectable by the Extreme UltraViolet Explorer Spectrometers are predicted. The computation indicates the presence of several highly ionized iron lines in the EUV spectral region.…
Modeling the X-ray spectrum of Kepler's supernova remnant.
Ballet, J.; Decourchelle, A.
We introduce realistic initial conditions for the ejecta density profile (power law) and propose to explain the silicon, sulphur and iron excess seen in Kepler's supernova remnant as associated with shocked enriched ejecta. We assume the composition of the interstellar medium to be solar. We describe the hydrodynamic interaction between the ejecta…
Hydrodynamic model of Kepler's supernova remnant constrained by EINSTEIN and EXOSAT X-ray spectra.
Ballet, J.; Rothenflug, R.; Magne, B. +1 more
We have used the EXOSAT spectrum of Kepler's supernova remnant (including the Fe K line and the high-energy continuum) to further constrain its models. On the basis of the large abundances of Si, S and Fe required by a Sedov model, we have focused on models of young supernova remnants in which the reverse shock (propagating into the stellar ejecta…