Search Publications
EXOSAT X-ray observations of the eclipsing magnetic cataclysmic variable EX Hya.
Mason, K. O.; Cordova, F. A.; Rosen, S. R.
Mechanisms for generating the 67-min rotational X-ray modulation in EX Hya are exmined. It is concluded that the dominant process is probably absorption in material accreting onto the polar regions of the white dwarf which is symmetrically distributed about the rotation axis due to the angular offset of the dipole field. The X-ray emitting region …
A survey of the galactic plane with EXOSAT.
Warwick, R. S.; Watson, M. G.; Turner, M. J. L. +2 more
The distribution of 2 - 6 keV X-ray emission in the galactic plane in the first and fourth galactic quadrants has been measured in a series of scanning observations with the medium-energy proportional counters on EXOSAT. The results are presented as contour maps and in the form of a catalogue of 70 discrete sources.
The 1985 May superoutburst of the dwarf nova OY Carinae - II. IUE andEXOSAT observations.
Sonneborn, G.; van Paradijs, J.; Charles, P. A. +4 more
The authors present ultraviolet (IUE) and X-ray (EXOSAT) observations of the eclipsing dwarf nova OY Carinae during the superoutburst of 1985 May. From the lack of X-ray eclipse and UV behaviour they deduce that the X-ray flux originates in an optically thin corona comparable in size to the Roche lobe, and not directly from the white dwarf or boun…
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…
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…
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…
EXOSAT observations of variable coronal X-ray emission from the youngK dwarf AB Doradus (= HD 36705).
White, N. E.; Collier Cameron, A.; Bedford, D. K. +2 more
We present the results of a search for rotationally-modulated X-ray emission from the young KO dwarf AB Doradus, using the low- and medium-energy detectors on board the EXOSAT spacecraft. Two sets of observations were obtained, each covering all or nearly all of the 0.514 day rotation period of the star, in 1984 December and 1986 January. A single…
GK Per : X-ray observations in quiescence.
King, A. R.; Watson, M. G.; Norton, A. J.
Two X-ray observations of GK Per in quiescence made with Exosat are presented. The X-ray light curve obtained on both occasions shows clear evidence for the 351-s pulse period first discovered during an earlier outburst. The pulse profile in the first of the two quiescent observations is similar to that observed during outburst, albeit with lower …
Variable low-energy absorption in the X-ray spectrum of ESO 103-G35.
Turner, T. J.; Warwick, R. S.; Pounds, K. A.
EXOSAT observations of the Seyfert 1.9 galaxy, ESO 103-G35, have revealed that this source has a heavily absorbed and variable low-energy X-ray spectrum. Specifically the inferred column density was observed to decrease from ~1.7x10^23^ to ~1.0x10^23^ cm^-2^ over a 90-day period. This variation is interpreted in terms of an X-ray absorbing screen …