Search Publications
Measurements of the Gas Temperature and Iron Abundance Distribution in the Coma Cluster
Hughes, John P.; Gorenstein, P.; Fabricant, D.
The medium energy X-ray detectors onboard the EXOSAT Observatory have been used to determine the gas temperature at several positions in the Coma Cluster of galaxies. We find evidence at greater than 95% confidence for a higher temperature in the center of the cluster than in a position approximately 45' off-center. No difference in iron abundance…
Evidence for rotationally modulated variability in O star winds.
Prinja, Raman K.
The nature of variability observed in the UV resonance line P Cygni profiles of four O stars is interpreted in terms of recurrent episodes of low-velocity broad absorption enhancements evolving into high-velocity narrow absorption components. Profile fitting techniques are used to determine the central velocities of the (multiple) features. The re…
Variability of the soft excess in the Seyfert I galaxy MKN 335.
Turner, T. J.; Pounds, K. A.
The luminous Seyfert I galaxy Mkn 335 was observed by EXOSAT on six occasions between 1983 November 5 and 1985 December 24. A previous analysis of the 1984 December 6 observation revealed a two-component spectrum, with a hard power law dominant above ~2 keV on which was superimposed a strong soft X-ray excess in the 0.1-2 keV band of the EXOSAT lo…
IUE Observations of Z Andromedae: Spectral Variations during Quiescence and a Physical Model
Fernandez-Castro, Telmo; Cassatella, Angelo; Gimenez, Alvaro +1 more
The authors describe the results of an extensive monitoring of the ultraviolet spectrum of the symbiotic star Z And based on high- and low-resolution IUE observations made during 1978 - 1982, when the star was in a phase of quiescence. Large variations of the Balmer continuum and emission-line intensities where observed on a time scale of about 76…
4U 1626-67: The Binary with the Smallest Known Mass Function
van der Klis, M.; Verbunt, F.; Rappaport, S. +3 more
The pulsating X-ray source 4U 1626-67 is an accreting neutron star in a binary system with a very low mass companion. The authors observed the source with EXOSAT continuously for 23 hr on 1986 March 30 - 31 UT. These observations allow them to set a stringent upper limit on the projected semimajor axis of the orbit of the neutron star. The corresp…
An EXOSAT observation of an X-ray flare and quiescent emission from the RS CVn binary sigma2 CrB.
Mewe, R.; Brinkman, A. C.; van den Oord, G. H. J.
The RS CVn binary sigma2 Coronae Borealis was observed with medium-energy and low-energy detectors and the transmission grating spectrometer aboard EXOSAT, and a strong X-ray flare rising within about five minutes and lasting more than two hours was detected. The temperature rises steeply within three minutes from 19 MK to a value well above 70 MK…
The discovery of orbital dips in the soft X-ray emission of U GEM during an outburst.
King, A. R.; Watson, M. G.; Mason, K. O. +1 more
A series of Exosat and IUE observations of the dwarf nova U Geminorum have been made during the decline from an unusually long outburst that occurred in 1985 October and November. A strong soft X-ray flux was recorded which is modulated with the orbital period of the binary. The modulation takes the form of broad, deep dips whose morphology change…
X-ray observations of the 50-min dipping source XB 1916-053.
Mason, Keith O.; Smale, Alan P.; White, Nick E. +1 more
Three EXOSAT observations of the low-mass X-ray binary XB 1916-053 have revealed extreme variability in the appearance of the dips, ranging from complete absence to two broad, deep dips per 50-min cycle. These dips are believed to result from the obscuration of the central X-ray source by azimuthal structure in the accretion disc. The X-ray spectr…
Stellar coronae with EXOSAT : broad band spectroscopy of nearby coronal sources.
Schmitt, J. H. M. M.; Monsignori-Fossi, B. C.; Landini, M. +1 more
Broad-band observations of stellar coronae obtained with the Low Energy experiment on board the Exosat satellite are presented, together with a technique for the analysis of Exosat low-energy data. The limitations of filter spectroscopy with Exosat are discussed. Specific relationships are provided for extracting physical quantities (temperature, …
X-ray and ultraviolet observations of Markarian 421.
Bromage, G. E.; Warwick, R. S.; George, I. M.
We present the results of a detailed study of the BL Lacertae type object Markarian 421 (Mrk 421) based upon EXOSAT and IUE observations made during 1984 and 1985. In the X-ray band Mrk 421 exhibits significant variability on time-scales typically of the order of a day with a minimum e-folding time-scale, t_v_, of ~5x10^4^s. There is some indicati…