Research publications: Recent submissions
Now showing items 8741-8760 of 9764
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The variability in the UV resonance lines of the cataclysmic variables MU Cen, AH Her and QU Car
(1994)We present a time-variability study of the uV resonance lines Nv 1240, Si iv 1397 and C iv 1549 in the dwarf novae AH Her and MU Cen and the nova-like variable QU Car. The main findings are as follows. (i)Virtually no ... -
Observations of the IR recombination line emission from massive young stellar objects
(1995)We present new, high-resolution observations of the infrared H I emission lines of massive YSOs. The widths of the Br alpha, Brgamma and Pfgamma lines indicate outflowing material with velocities of 100-200 km s^-1 for all ... -
The application of Monte Carlo methods to the synthesis of spectral line profiles from accretion disc winds
(1995)A Monte Carlo line profile synthesis method is presented which allows the radiative transfer of resonantly scattered lines through a stellar wind to be solved exactly. The resulting code is designed to be used primarily ... -
Eclipse observations of an accretion disc wind
(1995)The Goddard High Resolution Spectrometer on the Hubble Space Telescope has been used to monitor, through eclipse, the C iv 1550-A and He ii 1640-A lines in the spectrum of the nova-like cataclysmic variable UX UMa. Previous ... -
The donor star of the long-period dwarf nova DX-Andromedae
(1993)Spectroscopic observations of the long-period dwarf nova DX Andromedae are reported which show that it has a binary period of 0.44167 d, a secondary radial velocity amplitude of 107 km/s, and a projected rotational velocity ... -
The ionization state of the winds from cataclysmic variables without classical boundary layers
(1993)We have calculated a grid of detailed photoionization models for the stellar winds in non-magnetic cataclysmic variables. In the light of evidence which questions the existence of a classical hot, luminous boundary layer ... -
Variability in the UV resonance lines of the cataclysmic variable V795 Herculis (PG-1711 + 336)
(1992)Variability in the UV resonance lines from the cataclysmic variable V795 Her is investigated on the basis of a total of 28 IUE SWP low-resolution spectra. Significant line profile fluctuations are evident in the C IV 1549 ... -
On the origin of the HI line emission associated with massive young stellar objects
(1992)The problem of interpreting the H I line emission associated with massive young stellar objects is addressed by comparing results of LTE calculations of H I Br-alpha and Pf-gamma profiles with observations of the exciting ... -
Time-dependence of the UV resonance lines in the cataclysmic variables YZ CNC, IR GEM and V3885-SGR
(1992)Orbital variations are observed in the UV resonance lines of YZ Cnc, IR Gem and V3885 Sgr. Optical spectroscopic observations of YZ Cnc show that the maximum absorption in the UV lines occurs about 0.7-0.8 orbits after the ... -
Ultraviolet observations of the long-period dwarf nova DX and in outburst
(1991)Ultraviolet observations of the little-studied dwarf nova, DX And, are presented. The observations were made with the International Ultraviolet Explorer satellite during the late stages of a rise to outburst maximum in ... -
Boundary-layer temperatures in high accretion rate cataclysmic variables
(1991)The Zanstra method is used to derive limits on boundary-layer temperatures in eclipsing dwarf novae during outburst and nova-like variables, using the observed He II 1640 and 4686 A recombination lines. It is assumed that ... -
A radial velocity study of the companion to the central star of Abell 35
(1997)We report the results of a radial velocity study of BD - 22.3467 deg (LW Hya), the cool companion to the subdwarf central star of the planetary nebula Abell 35. Estimates for its radial velocity have been obtained by cross ... -
Helium absorption and emission towards Theta^1 ORI C
(1997)The Hei absorption and emission systems towards Theta^1Ori C, the exciting star of the Orion Nebula, are investigated. To this end, high-resolution near-infrared long-slit spectra centred on the Hei 1.083-μm and Brgamma ... -
Pre-eclipse dips in the ultraviolet light curves of two eclipsing nova-like cataclysmic variables
(1997)Observations of the eclipsing nova-like variables UX UMa and RW Tri with the Hubble Space Telescope reveal substantial orbital modulations in their UV light. These modulations have a minimum about a quarter of an orbital ... -
Eclipses of accretion disc winds in cataclysmic variables : an atlas of theoretical CIV line profiles and line flux light curves
(1996)A grid of simulated eclipses of the wind-formed CIV resonance line in high-state, non-magnetic cataclysmic variables is presented. On this, trends in pre- and mid-eclipse line profiles and also in the light curves of ... -
New measurements of the 4He abundance in galactic HII
(1998)Preliminary results of the 4He relative abundance determination from Radio Recombination Lines observations at different frequencies in the Orion, Rosette and W3 HII regions are presented. The Orion HII region has been ... -
Engaging students via student-unique Weekly Assessed Tutorial Sheets: A four year review
(2009)Following unacceptable examination performance in a core engineering module, (fluid mechanics and thermodynamics), an alternative and innovative approach to assessment was developed. The new approach centered on the use ... -
The first generation of Virgo cluster dwarf elliptical galaxies?
(2009)In the light of the question whether most early-type dwarf (dE) galaxies in clusters formed through infall and transformation of late-type progenitors, we search for an imprint of such an infall history in the oldest, most ...