Search Publications
A deep survey of heavy element lines in planetary nebulae - I. Observations and forbidden-line densities, temperatures and abundances
Tsamis, Y. G.; Barlow, M. J.; Liu, X. -W. +2 more
We present deep optical spectrophotometry of 12 Galactic planetary nebulae (PNe) and three Magellanic Cloud PNe. Nine of the Galactic PNe were observed by scanning the slit of the spectrograph across the nebula, yielding relative line intensities for the entire nebula that are suitable for comparison with integrated nebular fluxes measured in othe…
Heavy-element abundance patterns in hot DA white dwarfs
Barstow, M. A.; Bruhweiler, F. C.; Holberg, J. B. +5 more
We present a series of systematic abundance measurements for 25 hot DA white dwarfs in the temperature range ~20 000-110 000 K, based on far-ultraviolet spectroscopy with the Space Telescope Imaging Spectrograph (STIS)/Goddard High Resolution Spectrograph (GHRS) on-board Hubble Space Telescope, IUE and FUSE. Using our latest heavy-element blankete…
Complex optical-X-ray correlations in the narrow-line Seyfert 1 galaxy NGC 4051
Netzer, H.; Uttley, P.; Shemmer, O. +1 more
This paper presents the results of a dense and intensive X-ray and optical monitoring of the narrow-line Seyfert 1 galaxy NGC 4051 carried out in 2000. Results of the optical analysis are consistent with previous measurements. The amplitude of optical emission-line variability is a factor of 2 larger than that of the underlying optical continuum, …
Circumstellar features in hot DA white dwarfs
Barstow, M. A.; Bruhweiler, F. C.; Holberg, J. B. +1 more
We present a phenomenological study of highly ionized, non-photospheric absorption features in high spectral resolution vacuum ultraviolet spectra of 23 hot DA white dwarfs. Prior to this study, four of the survey objects (Feige 24, REJ 0457-281, G191-B2B and REJ 1614-085) were known to possess these features. We find four new objects with multipl…
The planetary nebula K 1-2 and its binary central star VW Pyx
Exter, K. M.; Pollacco, D. L.; Bell, S. A.
New data are presented of the post-common-envelope binary VW Pyx and its associated planetary nebula (PN), K 1-2. The central star is found to be a single-lined (and possibly double-lined) spectroscopic binary and is a good candidate for a system in which the main-sequence secondary star is more massive than the subdwarf primary star. The old PN h…
FUSE and HST ultraviolet observations of the disc wind of RW Sextantis
Knigge, C.; Prinja, R. K.; Long, K. S. +4 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) satellite time-series data of the low-inclination, nova-like cataclysmic variable RW Sex. The data span the wavelength range between ~905 and 1188Å, which contains the resonance lines of CIII, NIII, SIV, PV, SVI and OVI. All these spectral lines are present in the form of blueshifted absorpt…
Mid-infrared imaging of the dust shell around the post-asymptotic giant branch star HD 161796
Gledhill, T. M.; Yates, J. A.
We present mid-infrared (IR) images of HD 161796 (IRAS 17436+5003), taken with the OSCIR imager on the Gemini North Telescope, that resolve for the first time the thermal emission structure of the dust shell around this post-asymptotic giant branch (AGB) star. As well as a basic axisymmetric structure, the observations show deviations from axisymm…
QU Car: a very high luminosity nova-like binary with a carbon-enriched companion
Long, Knox S.; Drew, Janet E.; Hartley, Louise E. +1 more
QU Car is listed in cataclysmic variable star catalogues as a nova-like variable. This little-studied, yet bright interacting binary is re-appraised here in the light of new high-quality ultraviolet interstellar line data obtained with STIS on-board the Hubble Space Telescope. The detection of a component of interstellar absorption at a mean local…
Chromospheric activity and unique solution of SZ Psc
Kang, Young Woon; Lee, Woo-Baik; Kim, Ho-il +1 more
We have confirmed that the MgII h and k emission lines of SZ Psc are mainly enhanced by the K subgiant component of the system, using the radial velocities reduced from the emission lines. The intensity variation of the emission line is correlated with the orbital phase of SZ Psc. The shape of light curves of SZ Psc were changing every season. The…
The deuterium abundance in the z= 0.7 absorber towards QSO PG1718+4807
Webb, J. K.; Carswell, R. F.; Lanzetta, K. M. +1 more
We report on a further analysis of the ratio of deuterium to hydrogen (D/H) using Hubble Space Telescope (HST) spectra of the z= 0.701 Lyman limit system towards the quasi-stellar object (QSO) PG1718+481. Initial analyses of this absorber found it gave a high D/H value, 1.8-3.1 × 10-4, inconsistent with several higher redshift measureme…