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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-…
An activity-rotation relationship in F-M dwarfs from MG II H and K flux.
Doyle, J. G.
Mg II h and k fluxes are given for late-type dwarfs whose rotation periods are known. A good correlation between an activity parameter Rhk (represented by the ratio of Mg II h and k luminosity to bolometric luminosity) versus the Rossby-number is found for main-sequence stars F to late M. Both single and binary stars are found to follow…
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…
EXOSAT observations of the SNR PKS 1209-52.
Culhane, J. L.; Branduardi-Raymont, G.; Kellett, B. J. +3 more
Spatially resolved spectroscopy of the supernova remnant PKS 1209-52 and the point source within it is presented, based on observations made with the EXOSAT PSD detector. The authors find evidence that the shock front of the supernova remnant is interacting with an interstellar cloud. The data further indicate that the whole remnant is not in pres…
Quasi-periodic oscillations in the X-ray flux of GX 3+1 (4U 1744-26).
van Paradijs, J.; van der Klis, M.; Lewin, W. H. G. +7 more
GX 3+1, one of the brightest X-ray sources, was observed with EXOSAT in 1985 for 8.5 hr on March 24 - 25, and for 16 hr on September 4. During both observations the flux levels varied by about 20 per cent. The mean flux in September was about 8 per cent lower than in March. Throughout the March 24 - 25 observations, low-frequency noise (LFN) was o…
Radio detection of the Be star psi Persei.
Waters, L. B. F. M.; Lamers, H. J. G. L. M.; Taylor, A. R. +2 more
The authors present the results of a VLA survey for radio emission from a sample of Be stars having strong excess emission in the IRAS bands. Radio emission was detected from one star, ψ Persei. The radio flux density, together with nearly simultaneous ultraviolet and near-infrared observations, argue strongly against a spherically symmetric model…
X-ray and optical flickering in EF Eri.
King, A. R.; Watson, M. G.; Williams, G. A.
A study of the short-time-scale variability of the polar system EF Eri is presented based on simultaneous hard and soft X-ray monitoring with the Exosat Observatory and optical photometry from CTIO. The observations are used to investigate the nature of the flickering in this system, and the correlations between the variability in the three bands.…