Search Publications
X-ray observations of the Ophiuchus, PKS 0745-191 and Cygnus-A clusters of galaxies.
Fabian, A. C.; Mushotzky, R. F.; Nulsen, P. E. J. +4 more
The authors report observations of the X-ray emission from three bright clusters of galaxies at low Galactic latitudes; the Ophiuchus, PKS 0745-191 and Cygnus-A clusters. Temperatures and iron abundances are determined from EXOSAT spectral data. Images of the Ophiuchus cluster show it to have a high central density and a cooling flow. The authors …
Discovery of a strong soft X-ray excess in MKN 335 - evidence for an accretion disc ?
Turner, T. J.; King, A. R.; Pounds, K. A. +2 more
Exosat observations of Mkn 335 reveal a hard power-law spectrum above about 1 keV, typical for Seyfert 1 galaxies, but with unusually strong variability on time-scales of about 1-2 hr. In addition, an intense soft X-ray component is found to dominate the overall spectrum of Mkn 335 below about 0.6 keV. Both soft and hard components increased in st…
Multiwavelength monitoring of the dwarf nova VW Hydri. V. EXOSAT observations.
Heise, J.; van der Woerd, H.
Exosat X-ray observations of VW Hyi during three normal outbursts and one superoutburst were obtained in 1984. The decrease in X-ray flux by a factor of 1.2-1.6 during the quiescent periods between outbursts implies that the accretion rate onto the white dwarf decreases by about the same factor, consistent with emission from an optically thin hot …
High-frequency oscillations from CIR X-1.
Tennant, A. F.
The author reports results from an EXOSAT observation of Cir X-1 during which strong, low-frequency (5-20 Hz) quasi-periodic oscillations (QPO) were detected. QPO were also detected at much higher frequencies (100-200 Hz). These high frequencies are consistent with rotation periods in the inner accretion disc region. High-frequency QPO lend weight…
Constraints on the mass-radius relation of the neutron star in 4U 1746-37/NGC 6441.
van Paradijs, J.; Lewin, W. H. G.; Vacca, W. D. +4 more
An analysis of 12 hours of continuous EXOSAT observations of 4U 1746-37 in NGC 6441, obtained between September 9 and 10, 1985, puts constraints on its mass-radius relation. The spectral shape of the persistent X-ray flux is well fitted by a thermal bremsstrahlung spectrum, with a kT temperature varying between 7.5 and 9.8 keV, and an interstellar…
Simultaneous observations of the X-ray and optical eclipse of SS 433 and their impplications.
Mazeh, T.; Matsuoka, M.; Watson, M. G. +9 more
The authors report on the results of coordinated X-ray and optical observations of SS433 made over one binary cycle. The optical light curve shows SS433 to be in a typical state, with two unequal minima separated by 0.5 in phase. The X-ray observations show reduced intensity coincident with the deeper, primary optical minimum. The authors interpre…
A 25 min modulation from the vicinity of the unusually soft X-ray source X 0142+614.
White, N. E.; Branduardi-Raymont, G.; Giommi, P. +5 more
The results of three Exosat observations of X0142+614 made in August 1984 and November and December 1985 are reported. A 25-min coherent modulation was detected during the first observation, but not during the following two. The modulation peak-to-peak amplitude was 55 percent between 3 and 8 keV and less than 1 percent between 1 and 3 keV. The 1-…
Detailed EXOSAT and optical observations of the intermediate polar 3A0729+103 : discovery of two medium energy X-ray emission regions.
McHardy, I. M.; Pye, J. P.; Fairall, A. P. +1 more
EXOSAT observations of the intermediate polar cataclysmic variable 3A0729+103 reveal a strong orbital modulation, with the 2 - 4 keV X-rays being significantly more modulated than the 4 - 6 keV X-rays, indicative of photoelectric absorption. Contemporaneous optical spectroscopy shows that the X-ray minimum occurs at maximum velocity of recession o…
The X-ray properties of 3A 1907+09.
Cook, M. C.; Page, C. G.
A series of EXOSAT observations of the high-mass X-ray binary 3A1907+09 in 1984 early June show a spin-down of the neutron star since the discovery of X-ray pulsations in 1983 September by Tenma. The mildly eccentric orbit derived from Tenma data is confirmed and orbital parameters are refined. The pulse-averaged spectra were consistent with a har…
An EXOSAT observation of 1.5 orbital cycles of the 0.7 day short-period RS CVn system ER Vul.
Parmar, A. N.; White, N. E.; Culhane, J. L. +1 more
Two Exosat observations of the short-period 0.7-day eclipsing RS Cvn binary system ER Vul are reported. The first observation in October 1984, lasted for 3 hr, while the second in May 1985, covered 1.5 orbital cycles. The overall counting rate decreased by a factor of about 2 in the 6 months separating the two observations. No strong orbital modul…