Search Publications
Measuring the black hole masses of high-redshift quasars
McLure, R. J.; Jarvis, M. J.
A new technique is presented for determining the black hole masses of high-redshift quasars from optical spectroscopy. The new method utilizes the full-width at half-maximum (FWHM) of the low-ionization MgII emission line and the correlation between the broad-line region (BLR) radius and the continuum luminosity at 3000 Å. Using archival ultraviol…
An empirical calibration of star formation rate estimators
Terlevich, Roberto; Terlevich, Elena; Rosa-González, Daniel
The observational determination of the behaviour of the star formation rate (SFR) with look-back time or redshift has two main weaknesses: (i) the large uncertainty of the dust/extinction corrections, and (ii) that systematic errors may be introduced by the fact that the SFR is estimated using different methods at different redshifts. Most frequen…
Testing the line-driven disc wind model: time-resolved ultraviolet spectroscopy of IX Vel and V3885Sgr
Knigge, C.; Long, K. S.; Proga, D. +2 more
To confront the predictions of the most recent line-driven disc wind models with observational evidence, we have obtained Hubble Space Telescope (HST ) STIS (1180-1700Å) echelle spectra of the nova-like variables IX Vel and V3885Sgr at three epochs. The targets were observed in time-tag mode for ~2000s on each occasion, allowing us to study the sp…
The massive double-lined O-type binary HD 165052
Barbá, R. H.; Morrell, N. I.; Arias, J. I. +3 more
We present a new optical spectroscopic study of the O-type binary HD 165052 based on high- and intermediate-resolution CCD observations. We re-investigated the spectral classification of the binary components, obtaining spectral types of O6.5V and O7.5V for the primary and secondary, respectively, finding that both stars display weak CIIIλ5696 emi…
On the source of the flaring activity in AB Doradus: the UV spectral signatures
Gómez de Castro, Ana I.
AB Dor is a young, 30-Myr-old, low-mass star with a short rotation period and strong flaring activity. In this work, a detailed analysis of the flaring activity is carried out based on ultraviolet spectral tracers of hot (T ~105 ) plasma, namely HST /GHRS profiles of the Civ[uv1] and Siiv[uv1] lines. The quiescent component has been sub…
The anomalous ultraviolet light curves and IUE spectra of β Lyrae revisited
Linnell, A. P.
Recent studies of β Lyrae have proposed several possible models to explain the anomalous ultraviolet light curves of that mass-transfer binary system. This paper subjects four proposed models to tests involving a comparison of system synthetic spectra with the observed spectra and a comparison of synthetic light curves, based on synthetic photomet…
Time-resolved ultraviolet spectroscopy of the compact interacting binary QU Car
Long, K. S.; Drew, J. E.; Hartley, L. E.
We present Hubble Space Telescope STIS (1160-1700 Å) echelle spectra of the cataclysmic variable (CV) star QU Car, at three epochs. In catalogues this binary is classified as a nova-like variable. QU Car was observed three times in time-tag mode for 2300, 2600 and 2600 s, allowing us to study the spectral time evolution on time-scales down to ~10 …
A search for circumstellar material around B-type stars in the Galactic halo
Dufton, P. L.; Keenan, F. P.; Rolleston, W. R. J. +2 more
19 B-type stars, selected from the Palomar-Green Survey, have been observed at infrared wavelengths to search for possible infrared excesses, as part of an ongoing programme to investigate the nature of early-type stars at high Galactic latitudes. The resulting infrared fluxes, along with Strömgren photometry, are compared with theoretical flux pr…