Search Publications
Anomalously high intercombination line ratios in symbiotic stars; extreme Bowen pumping ?
Feibelman, W. A.; Bhatia, A. K.; Kastner, S. O.
International Ultraviolet Explorer observations of the ratio of the O III intercombination lines near 1660 A are assembled, showing that the observed ratios in symbiotic stars are significantly higher than the theoretically predicted optically thin limit of 2.5. The presence of an enhancing physical process is thereby indicated. It is suggested th…
EXOSAT observations of the remnant of SN 1006.
Jones, L. R.; Pye, J. P.
The remnant produced by the supernova explosion of AD 1006 has been studied in X-rays with the Exosat Observatory. Images in the energy range 0.1-2 keV with resolution sufficient to resolve the limbs, obtained through three different filters, reveal a limb-brightened nebula containing clumps of emission and displaying large spectral variations wit…
Ultraviolet spectra of a large sample of quasars. I. Data and data reduction.
Gondhalekar, P. M.
Ultraviolet spectrophotometric data on all quasars (Z_e_ > 0.1) obtained with IUE from 1978 to the end of 1986 have been retrieved from IUE archive and re-extracted directly from the photometrically corrected images. A spectrum extraction procedure was used to maximize the signal-to-noise ratio and discriminate against spurious events outside t…
EXOSAT X-ray observations of the eclipsing magnetic cataclysmic variable EX Hya.
Mason, K. O.; Cordova, F. A.; Rosen, S. R.
Mechanisms for generating the 67-min rotational X-ray modulation in EX Hya are exmined. It is concluded that the dominant process is probably absorption in material accreting onto the polar regions of the white dwarf which is symmetrically distributed about the rotation axis due to the angular offset of the dipole field. The X-ray emitting region …
A survey of the galactic plane with EXOSAT.
Warwick, R. S.; Watson, M. G.; Turner, M. J. L. +2 more
The distribution of 2 - 6 keV X-ray emission in the galactic plane in the first and fourth galactic quadrants has been measured in a series of scanning observations with the medium-energy proportional counters on EXOSAT. The results are presented as contour maps and in the form of a catalogue of 70 discrete sources.
The ultraviolet continuum of quasars -I. The shape of the continuum, continuum reddening and intervening absorption.
Wilson, R.; Gondhalekar, P. M.; Obrien, P. T.
We present ultraviolet data for a sample of 81 quasars covering a wide redshift and luminosity range. After allowing for the effect of absorption due to intervening clouds, the intrinsic optical and ultraviolet continuum for quasars is found to steepen towards shorter wavelengths from ~ 1 micron to ~800 A by ~1 in spectral index. The mean ratio of…
An accretion disc in the broad-line radio galaxy 3C 390.3 ?
Penston, M. V.; Perez, E.; Moles, M. +2 more
The permitted broad component of the Hβ emission line in the broadline radio galaxy (BLRG) 3C390.3 presents a double-peaked structure, similar to that seen in cataclysmic variables. The profile of the line is well fitted by a relativistic accretion disc with an intermediate inclination to the line-of-sight.
The interstellar extinction in the open clusters TR 14, TR 15, TR 16/Cr 232 and CR 228 in NGC 3372 New near-infrared photometry.
Roth, M.; Ruiz, M. T.; Tapia, M. +1 more
Near-infrared JHKL photometry of more than 200 stars, members of the open clusters Tr 14, Tr 15, Tr 16, Cr 228 and Cr 232 in the Carina Nebula are presented. From comparing these results with the available visual photometry and spectroscopy, it is found that, except in Tr 15, the intracluster reddening is characterized by a 'normal' extinction law…
Opacity enhancements in the stellar wind of 68 Cygni - not "shells" or "puffs".
Howarth, Ian D.; Prinja, Raman K.
Results presented from a study of variability in the stellar wind of 68 Cyg [O7.5 III((f))], based on 33 IUE high-resolution spectra taken over ≡7 days in 1986 August. Significant changes are evident in the Si IV resonance line profiles on time-scales as short as ≡1 hr; these changes are characterized by broad low-velocity (≡0.55v) absorption enha…
The 1985 May superoutburst of the dwarf nova OY Carinae - II. IUE andEXOSAT observations.
Sonneborn, G.; van Paradijs, J.; Charles, P. A. +4 more
The authors present ultraviolet (IUE) and X-ray (EXOSAT) observations of the eclipsing dwarf nova OY Carinae during the superoutburst of 1985 May. From the lack of X-ray eclipse and UV behaviour they deduce that the X-ray flux originates in an optically thin corona comparable in size to the Roche lobe, and not directly from the white dwarf or boun…