Search Publications
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…
Dwarf novae in outburst : modelling the observations.
Verbunt, F.; Pringle, J. E.; Wade, R. A.
Time-dependent accretion-disk models are constructed and used to calculate theoretical spectra in order to try and fit the ultraviolet and optical observations of outbursts of the two dwarf novae VW Hydri and CN Orionis. It is found that the behavior on the rise to outburst is the strongest discriminator between theoretical models. The mass-transf…
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…
Constraints on the outer atmospheric structure of late-type giant stars with IUE : methods and application to Arcturus (alpha Boo K2III).
Judge, P. G.
Methods for empirically analyzing the emission lines formed in the outer atmospheres of late-type low-gravity stars are described and applied to the K2III star Alpha Boo. The methods are based on electron-density measurements, emission-measure analysis, and determination of the optical depths of emission lines. The reduction and measurement of IUE…
The ultraviolet spectrum and interstellar environment of HD 50896.
Howarth, Ian D.; Phillips, A. Paul
By combining the results from 52 IUE spectra of the WN5 star HD 50896 the authors have constructed a photometrically precise, flux-calibrated, mean high-resolution (R ≈ 104) data set covering the wavelength range 1150 - 3274 Å. They give measurements of fluxes and widths for all detected emission lines and P Cygni profiles; approximatel…
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,…
Constraints on the outer atmospheric structure of late-type giants stars with IUE : application to alpha Tau (K5III) and beta Gru (M5III).
Judge, P. G.
Empirical constaints on the outer atmospheric structures of α Tau and β Gru are derived using high resolution spectra from the International Ultraviolet Explorer (IUE) satellite, with methods which have been described and applied to α Boo (K2III) in an earlier paper. These stars have IUE spectra which are typical of giant stars later than ∼K0 whic…
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…