Search Publications
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…
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…
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…
Detection of broad ultraviolet Fe II lines in the spectrum of NGC 1068.
Boksenberg, A.; Snijders, M. A. J.; Netzer, Hagai
Ultraviolet observations of the nucleus ofo NGC 1068, obtained by the IUE over a period of 5 yr, are combined to give a high signal-to-noise spectrum of this source. The ultraviolet stellar continuum, obtained by comparison with ground-based data, is subtracted to show the nuclear nonstellar component. The resulting spectrum shows clearly the pres…
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…
An ultraviolet and optical study of the broad-line radio galaxy 3C 382.
Perez, E.; Fosbury, R. A. E.; Tadhunter, C. N.
Ultraviolet spectra covering 13 separate epochs are presented for the extreme broad-line radio galaxy 3C 382. These show marked variability in both lines and continuum on a time-scale less than about 1 yr. The C IV 1550 A and L-alpha 1216 A lines follow the changes in the ultraviolet continuum but appear to have different profiles, the L-alpha 121…
A multi-wavelength study of the long-period AM HER system E2003+225 -II. Changes in the accretion geometry.
Mukai, K.; Maraschi, L.; van Paradijs, J. +7 more
The longest period AM Her system E2003+225 was observed on 1984 July 24 with IUE, with simultaneous optical spectroscopy and photometry from La Palma. The variations of the overall continuum from 1200 to 5000 Å with orbital phase allow a study of the different spectral components in the system. High-resolution optical spectra show complex line pro…
PKS 2005-489 : a very bright BL Lac object in a nearby galaxy.
Wamsteker, W.; Warwick, R. S.; Pettini, M. +2 more
The galaxy identified with the flat-spectrum radio source PKS 2005-489 has a bright and variable stellar nucleus with a brightest observed V magnitude of ≡13. The authors report radio, optical, UV and X-ray observations which indicate variability and power-law continua in each of these wavebands, leading to the conclusion that PKS 2005-489 is one …
Ultraviolet spectra of quasars in the redshift interval 0.3 to 2.0.
Wilson, R.; Gondhalekar, P. M.; Obrien, P.
UV spectroscopic observations of nine QSOs with z = 0.3-2.0, obtained with the IUE SWP and LWR(P) instruments during 1978-1983, are reported. The continuum emission is attributed to the combination of a 20,000-30,000-K blackbody (the source of most of the UV emission), Balmer emission, and a power-law component (extending to the X-ray emission). T…