Search Publications
An archival study of IUE observations of low-redshift quasars.
Cheng, F. H.; Fang, L. Z.
The emission-line and continuum characteristics of a sample of 18 low-redshift quasars from the IUE archives are presented. The spectral index (Fν ∝ ν-α) is found to have a mean value of 1.10±0.11, which is considerably steeper than the index of the same spectral region for high-redshift objects. The line ratios Lα/…
The spectroscopic orbit of HD 128220.
Howarth, Ian D.
HD 128220 is a double-lined binary containing a subdwarf O star. A new orbital solution is presented, based principally on IUE spectroscopy. The implications of the solution for the physical parameters of the subdwarf are discussed, with the results that MOsin3i = 1.6±0.7 M_sun;; ROsin3/2i = 1.2±0.4 R_su…
Sulphur compounds in cometary IUE spectra
Krishna Swamy, K. S.; Wallis, M. K.
Bands of S2 have been identified in several comets including Černis, Bowell, Churyumov-Gerasimenko, Encke, etc., covering a wide range in heliocentric distances. S2 seems to have been present in comet Halley even from 1985 early December when it was at 1.5 AU. The authors have also tentatively identified bands of the B-X syst…
The formation of iron features in the cooling spectrum of X-ray bursts.
Fabian, A. C.; Ross, R. R.; Foster, A. J.
A detailed calculation of the formation and detection of iron spectral features in X-ray bursts is presented. Observation of these features will enable the mass and radius of a neutron star to be estimated separately. Comptonization and free-free absorption and emission processes are taken into account, as well as the effects of iron in its last f…
A subdwarf's startling stellar wind.
Howarth, Ian D.
Selected observations of the subdwarf HD 128220B are presented to illustrate several remarkable properties of its stellar wind. The N V resonance doublet shows a typical P Cygni profile, but the C IV doublet shows a highly structured, strongly variable absorption profile with up to nine discrete velocity components present at any one time. Velocit…
Studies of calcium emission stars. I. HD 158393, a giant star in a binary system.
Lloyd Evans, T.; Balona, L. A.; Fekel, Francis C.
HD 158393 is a giant star of spectral type late G or early K which has moderately strong Ca II H and K emission cores. UBVRIJHK photometry and IUE spectra reveal a companion of type F0 - F2, luminosity class IV or V. Radial velocity data yield an orbit with a period of 31 day. The K and F stars have nearly equal mass, with a minimum value of 1.7 M…
The MG II line profile in the Seyfert galaxy NGC 4151 : a new outflowing component.
Gull, T. R.; Penston, M. V.; Snijders, M. A. J. +1 more
This paper examines the Mg II λλ2795, 2802 doublet in the Seyfert galaxy NGC 4151 at a higher resolution than has previously been used, searching for velocity systems in absorption and emission. Evidence is presented for a new, narrow, outflowing absorption system in Mg II having a velocity of 825 km s-1 relative to the Sun, -165 km s
Spectral variability of 4U 1145-619 during X-ray outburst.
Warwick, R. S.; Cook, M. C.
A series of observations of the X-ray pulsar 4U1145-619 were performed by EXOSAT during successive X-ray outbursts on this source in 1984 July and 1985 January. On all occasions the source exhibited a very hard power-law X-ray spectrum (photon spectral index ≡1.0) with a high-energy cut-off above ≡6 keV. The low-energy cut-off in the X-ray spectru…
Synchrotron X-ray haloes around gamma ray sources
Warwick, R. S.; Wolfendale, A. W.; Norton, A. J. +3 more
High energy γ-ray sources, epitomized by Cygnus X-3, may well be releasing significant fluxes of 1014eV electrons into their environment and these electrons can give synchrotron X-rays when deflected in the general interstellar magnetic field. A greatly simplified model for this mechanism is described in terms of electron diffusion para…
The ultraviolet variability X-ray pulsars : observations of VELA X-1,A 0535+26 and 4U 1145-619.
Coe, M. J.; Payne, B. J.
The IUE satellite has been used in a special trailed mode to search for modulation in the ultraviolet flux from the binary X-ray pulsars Vela X-1, A 0535+26 and 4U 1145-619. The trailing technique allows the UV spectrum from these sources to be sampled during the X-ray pulse cycle, with a resolution ≡1/10th of the pulse period. Modulations of 15 -…