Search Publications
NGC 6153: a super-metal-rich planetary nebula?
Barlow, M. J.; Cohen, M.; Liu, X. -W. +3 more
We have obtained deep optical spectra of the planetary nebula NGC 6153, both along its minor axis and by uniformly scanning a long slit across the whole nebula. The scanned spectra, when combined with the nebular total Hβ flux, yield integrated fluxes for all the lines (~400) in our spectra, which are rich in strong recombination lines from C, N, …
Quantitative analysis of WC stars: constraints on neon abundances from ISO-SWS spectroscopy
Hillier, D. John; Morris, Patrick W.; Crowther, Paul A. +3 more
Neon abundances are derived in four Galactic WC stars - γ2Vel (WR11, WC8+O7.5III), HD156385 (WR90, WC7), HD192103 (WR135, WC8) and WR146 (WC5+O8) - using mid-infrared fine-structure lines obtained with ISO-SWS. Stellar parameters for each star are derived using the non-local thermodynamic equilibrium model atmospheric code of Hillier &a…
The massive stellar content of the Hii region NGC 604 and its evolutionary state
Pérez, Enrique; González Delgado, Rosa M.
This paper analyses the integrated ultraviolet spectra taken with the International Ultraviolet Explorer (IUE) and optical ground-based spectra taken with the William Herschel Telescope (WHT) of the giant Hii region NGC 604. These data are complemented with ultraviolet (WFPC2 through F170W) and Hα (WFPC2 through F656N) images retrieved from the Hu…
The optical spectrum of the planetary nebula NGC 6543
Feibelman, W. A.; de Koter, A.; Hyung, S. +2 more
With the Hamilton echelle spectrograph at the Lick Observatory, emission-rich spectral lines of the planetary nebula NGC 6543 were secured in the wavelength range from 3550 to 10100Å. We chose two bright regions, ~8arcsec east and ~13arcsec north of the central star, the physical conditions and chemical abundances of which may differ as a result o…
HST ultraviolet observations of rapid variability in the accretion-disc wind of BZ Cam
Ringwald, F. A.; Prinja, Raman K.; Knigge, Christian +1 more
We present results from time-resolved Hubble Space Telescope (HST) GHRS ultraviolet spectroscopy of the nova-like cataclysmic variable BZ Cam. Extensive changes are recorded in the extended absorption troughs of the UV resonance line profiles, which betray a highly unsteady and continuously variable supersonic outflow. The large-scale line-profile…
Progress on a model for β Lyrae
Linnell, A. P.
It is generally accepted that β Lyrae is a massive mass-transfer system in which the more massive gainer is embedded in a thick accretion disc. No detailed, quantitative accretion disc model of the system, which fits both the available photometric and spectroscopic data, has been published. This paper considers a thick accretion disc model. An emp…
The discovery of photospheric nickel in the hot DO white dwarf REJ 0503-289
Werner, K.; Dreizler, S.; Barstow, M. A. +4 more
We present the first evidence for the direct detection of nickel in the photosphere of the hot DO white dwarf REJ 0503-289. While this element has been seen previously in the atmospheres of hot H-rich white dwarfs, this is one of the first similar discoveries in a He-rich object. Intriguingly, iron, which is observed to be more abundant than Ni in…
UV spectroscopy of the peculiar binary V Sagittae in a low state
Wood, Janet H.; Lockley, J. J.
In this paper we present the first phase-resolved, high-resolution, UV spectroscopy of V Sge. HST GHRS observations were obtained covering 1.5 orbital cycles of V Sge in a low state. We covered the Heii 1640 line and the Civ 1550 doublet alternately, and also obtained one spectrum covering Mgii 2800. We create continuum and line flux light curves …
Interstellar CO towards X Persei (HD 24534) - II. Two-component model
Kaczmarczyk, Grzegorz
The observations made by the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) of molecular CO in absorbing gas towards X Persei are reported. The two-component statistical equilibrium model incorporating radiative excitation of CO by line emission at the same velocity that originates in nearby molecular clouds ha…
Interstellar CO towards X Persei (HD 24534) - I. One-component model
Kaczmarczyk, Grzegorz
Data on molecular CO in absorbing gas towards X Per, from the International Ultraviolet Explorer (IUE) and the echelle mode of the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope, are reported. A statistical equilibrium model is used to recreate equivalent widths of CO bands and reproduce high-resolution GHRS spectra.…