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The Extremely X-Ray Bright Wolf-Rayet Star HD193793
Pollock, A. M. T.
The Einstein Observatory showed that Wolf-Rayet stars have a much larger range in the ratio of X-ray to bolometric luminosity than normal early-type stars. EXOSAT measurements of HD193T93 (WCT+abs) show it to be extremely X-ray bright. This result is probably not connected with the infra-red and radio outburst that the star underwent in 1977. Othe…
Multicomponent Analysis of Total Cos-B Gamma-Ray Data at Intermediate Latitudes
Strong, A. W.; Mayer-Hasselwander, H. A.; Bloemen, J. B. G. M. +1 more
The final COS-B database has been used to study the gamma-ray emission in the latitude range 10° < |b| < 20° in terms of a four component model. The emissivity spectrum of the local interstellar medium is derived and compared with that found in previous studies. The intensity of the inverse-Compton component is determined from the fitting pr…
IUE observations of the contact binary XY Leonis.
Vilhu, O.; Rucinski, S. M.
IUE observations (FES light curves, LWR Mg II emission data, and an SWP spectrum) obtained on June 11, 1982 are reported for XY Leo. The Mg II fluxes were measured at two primary minima, one secondary minimum, and one orbital quadrature. The data are presented in tables and spectra and analyzed. The orbital-average relative flux f(Mg II)/f(bol) is…
EXOSAT observations of a 2,000-s intensity dip in Seyfert galaxy NGC4151
Cruise, A. M.; Whitehouse, D. R.
Variations in the flux from active galactic nuclei (AGN) allow the testing of models of their emission mechanisms. Various suggestions for the energy generation in AGNs require the existence of a compact object, with X rays generated deep in that object's potential well and, therefore, X-ray luminosity related directly to the object responsible fo…
Photometric and UV spectroscopic observations of 22 VUL at eclipse : observational evidence for an extended chromosphere of a solar type G supergiant.
Che-Bohnenstengel, A.; Schroeder, K. -P.
The solar spectral type supergiant (G3 Ib-II) of the 22 Vul binary has been observed photometrically and spectroscopically during its recent eclipse of the B9 V companion. From the new photometric observations the eclipse data given by Parsons and Ake (1984) can be slightly improved (period = 249.21 ± 0.2 days, mideclipse: JD 2446191.6 ± 0.2). The…
IRAS observations of MKN 501 with quasi-simultaneous observations at radio, near-infrared and ultraviolet wavelengths.
Di Cocco, G.; Coe, M. J.; Spinoglio, L. +9 more
The authors present quasi-simultaneous observations at radio, far-infrared, near-infrared and ultraviolet wavelengths of the BL Lac object MKN 501. Specifically, they have observed the source with the IRAS satellite, and they show that the best power-law fit to the 12 to 100 µm data gives a slope of index α = 0.55±0.1. They show that the com…
The Variable Iron Line in CYGNUS-X-3
van der Klis, M.; Manzo, G.; Smith, A. +3 more
Cygnus X-3 was observed with the GSPC on board EXOSAT on several occasions, one observation lasting for 7 orbital cycles. The width W and centroid energy E of the iron emission feature near 6.7 keV show a smooth, correlated, sinusoidal-type modulation, the iron line being widest and E being lowest just before X-ray maximum. The line profile may sh…
Spectral variability of scorpius X-1, as observed with EXOSAT
Mewe, R.; Heise, J.; Brinkman, A. C. +3 more
EXOSAT measurements of Sco X-1 have been carried out with the 500 l/mm and 1000 l/mm grating spectrometers and simultaneously with the gas scintillation proportional counter (GSPC) on two occasions in August 1983. The first observing period, part of the instrument performance verification phase, on August 7 and 8, 1983, lasted for about twenty two…
Exosat observations of the galactic bulge X-ray source GX17+2
Sztajno, M.; Truemper, J.; Langmeier, A. +1 more
We have measured the X-ray flux of the bright galactic bulge source GX17+2 in the energy range 1-20 keV using the EXOSAT ME experiment. During 8 hours of continuous observation an X-ray flare was observed (lasting ~1 hr) followed by an intensity increase. The data show intensity dips with a quasiperiod of ~1.4 hours and quasi-periodic oscillations…
The August 1984 eclipse of 22 Vulpeculae.
Ake, T. B.; Parsons, S. B.; Hopkins, J. L.
The newly discovered eclipsing binary 22 Vul (G3 Ib-II + B9) was observed in and around the 1984 eclipse both with the IUE satellite and by photometrists at various ground-based observatories. The depth of total eclipse of the hot component was 0.05 mag in the V band, 0.14 in B, and 0.35 in U. Time of mideclipse is now established at JD2445942.3 (…