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A study of the continuum and iron K line emission from low-mass X-raybinaries.
White, N. E.; Branduardi-Raymont, G.; Hasinger, G. +4 more
It is possible to classify the spectral properties of the luminous X-ray sources which are thought to contain accreting neutron stars broadly according to whether or not the source is a coherent X-ray pulsar. In the present paper a study is reported of the spectral properties of a sample of six low-mass X-ray binaries (LMXRB). It is found that the…
Observations of type I X-ray bursts from CIR X-1.
Fabian, A. C.; Tennant, A. F.; Shafer, R. A.
EXOSAT has recently observed three X-ray bursts from the direction of Circinus X-1 which have all the properties of type I bursts. These bursts most likely originate from Cir X-1 and the authors therefore identify Cir X-1 as a neutron star and not a black hole. The properties of the new bursts, such as the ratio of the energy released between burs…
Doppler-shifted X-ray line emission from SS 433.
King, A. R.; Watson, M. G.; Brinkmann, W. +1 more
The authors present the results from a series of X-ray observations of SS433 made with the EXOSAT Observatory in 1983 - 1985 which show that strong iron line emission is present in its X-ray spectrum and displays large energy shifts which vary as a function of the 164-day precession phase. These energy shifts are entirely consistent with the Doppl…
The discovery of X-ray bursts from CIR X-1.
Fabian, A. C.; Tennant, A. F.; Shafer, R. A.
A sequence of eight X-ray flares was detected during an EXOSAT observation of the low-state Circinus X-1 (= BR Cir). The authors identify these flares with X-ray bursts from Cir X-1. The recurrence time, ratio of persistent flux to the time-averaged flux and indications of cooling during the bursts are all consistent with these bursts being type I…
The soft X-ray spectrum of NGC 4151.
Culhane, J. L.; Warwick, R. S.; Pounds, K. A. +1 more
EXOSAT observations of the Seyfert galaxy NGC 4151 over the period 1983 July - 1984 April have revealed a steeply decreasing flux in the 2 - 10 keV band. Other observations have shown that this coincided with a fall in the whole infrared-to-ultraviolet continuum and a marked weakening of the broad emission lines. The X-ray spectral shape, however,…
Rapid X-ray variability of the Seyfert galaxy MCG -6-30-15.
Turner, T. J.; Warwick, R. S.; Pounds, K. A.
Strong and continuous variability was detected in the X-ray emission of the Seyfert I galaxy MCG-6-30-15 during a 9 hr EXOSAT observation in July 1984. Changes in the 2-6 keV flux appear quasi-sinusoidal with a modulation depth of 40-50 percent and peak-to-trough time-scales as short as 1500 s. Although less well determined, due to a lower countin…
Neutron star model atmospheres - a comparison with MXB 1728-34.
Fabian, A. C.; Ross, R. R.; Foster, A. J.
A detailed comparison between the X-ray spectra calculated for model atmospheres in neutron stars and the observed spectra of X-ray bursts is presented. Comptonization and free-free absorption and emission processes are taken into account, as are the effects of iron in its last three states of ionization. Two types of model are formulated, a const…
A unique triple-peaked type-1 X-ray burst from 4U/MXB 1636-53.
van Paradijs, J.; van der Klis, M.; Lewin, W. H. G. +3 more
The authors report the detection, with EXOSAT, of an X-ray burst from 4U/MXB 1636-53, whose intensity profile shows three distinct peaks. A time-resolved spectral analysis of this burst shows that this triple-peaked profile, which is clearly visible in the bolometric flux variations, is not the result of a major radius expansion of the neutron sta…
EXOSAT observations of the Seyfert galaxy NGC 7469; rapid hard X-rayvariability and a soft X-ray excess.
Barr, P.
The results of a series of EXOSAT observations of the Seyfert 1 (and starburst) galaxy NGC 7469 performed in July 1984 are presented. During one observation, hard X-ray variability by a factor 2 within 5 hr was found, while the soft X-ray intensity remained constant. In addition the spectral data indicate an excess of soft X-ray emission over that…
A multi-wavelength study of the long-period AM HER system E2003+225 -I. The soft X-ray light curve and overall energy spectrum.
Mukai, K.; Maraschi, L.; Chiappetti, L. +10 more
X-ray, UV and optical data are presented of the longest period AM Her object, E2003+225, from October 12, 1983, together with a new linear polarization ephemeris. The optical and X-ray data were obtained simultaneously and the UV observations were carried out on the same day. A 6-hr observation with the Exosat 500 line/mm objective grating restric…