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EXOSAT observations of a strong soft X-ray excess in MKN 841.
Culhane, J. L.; Fabian, A. C.; Branduardi-Raymont, G. +6 more
EXOSAT observations of the spectrum of the Seyfert 1 galaxy MKN 841 show that it is well-fitted by a power law of photon index 1.6, similar to that of other Seyferts, and a large additional soft component. The X-ray luminosity over the observed band exceeds 4×1044erg s-1. A single-temperature blackbody fit to the soft X-rays …
The old nova GK Per : discovery of the X-ray pulse period.
King, A. R.; Watson, M. G.; Osborne, J.
EXOSAT observations of GK Per during an optical outburst are reported. The hard X-ray emission (greater than 2 keV) shows a strong coherent modulation at a period of 351 s, identifying GK Per as the latest member of the 'intermediate polar' subclass of magnetic cataclysmic variables. The X-ray pulse profile has a quasi-sinusoidal shape with mean a…
Ultraviolet spectral evolution and heavy element abundances in nova Coronae Austrinae 1981.
Williams, R. E.; Truran, J. W.; Wyckoff, S. +3 more
Nova CrA 1981, a moderately fast galactic nova, was systematically observed over a period of seven months with the IUE satellite. The initial evolution of the UV spectrum was similar to that of previously observed novae; however, several months after maximum, weak emission due to very high ionizating forbidden lines of Na, Mg, Al, and Si appeared,…
Continuous rapid X-ray variability and spectral changes in NGC 4051.
Elvis, M.; Watson, M. G.; Lawrence, A. +1 more
The observation of rapid X-ray variability in active galaxies is of great potential interest. In Seyfert galaxies, variability on a time-scale of days seems common, but fast (minutes-hours) variability is apparently very rare. In a variability survey with the HEAO-1 A2 experiment, Tennant and Mushotzky (1983) found only one object to vary on short…
Detailed observations of NGC 4151 with the IUE - IV. Absorption line spectrum and variability.
Tanzi, E. G.; Perola, G. C.; Boksenberg, A. +7 more
A detailed analysis is presented of the ultraviolet (λλ1150 - 3200 Å) absorption spectrum of the NGC 4151 Seyfert nucleus. The IUE data base consisted of high-dispersion (Δλ ≡ 0.2 Å) spectra at 5 epochs, and 137 low-dispersion (Δλ ≡ 4 - 8 Å) spectra at 31 epochs from 1978 February to 1980 May, together with further low-dispersion data in 1980 - 81…
The discovery of low-level iron K line emission from CYG X-1.
White, N. E.; Barr, P.; Page, C. G.
The results of seven observations of the X-ray spectrum of Cyg X-1, made using the gas scintillation proportional counter on board the Exosat Observatory are presented. The discovery of a broad emission feature at 6.2 keV is reported with an equivalent width of typically 120 eV. The line is resolved to have an FWHM of about 1.2 keV. There is no ev…
An X-ray, optical and radio study of PKS 0745-191 : a massive coolingflow.
McHardy, I.; Fabian, A. C.; Elvis, M. +7 more
The X-ray source 3A 0745-191 is identified with intracluster gas surrounding the giant galaxy containing the radio source, PKS 0745-191, which lies at z = 0.1. The gas is cooling at the unprecedented rate of 1000 M_sun;yr-1. Optical line-emitting gas extends more than 10 kpc from the centre of the galaxy and corroborates the high mass-f…
Investigation of a wind model for cataclysmic variable ultraviolet resonance line emission.
Verbunt, F.; Drew, J.
The present investigation of ionization and thermal structure in a spherically symmetric, radiatively driven wind emanating from the vicinity of a cataclysmic variable's white dwarf notes that wind ionization is always high for plausible wind and radiation field parameter values, and that resonance scattering dominates line formation at large radi…
EXOSAT soft X-ray observations of EX Hydrae.
Kahn, S. M.; Mason, K. O.; Cordova, F. A.
During a continuous 26 hour X-ray observation of the 98-min binary EX Hydrae using the CMA detector on EXOSAT, a 67-min modulation was detected with a pulse-fraction of about 30 per cent. The phase of the modulation coincides with that of the 67-min optical modulation which has a pulse-fraction of 15 per cent. The X-ray and optical pulse shapes ar…
IUE observations of HD 36705.
Rucinski, S. M.
HD 36705 is one of the most rapidly rotating (0.514-day) possibly single late-type (K0/2) stars known. The IUE was used to obtain ten LWR high resolution and five SWP low-resolution spectra in different phases of the rotational period. The FES light curve indicates a rather uniform coverage by spots during the observations. The Mg II emission line…