Search Publications
The Cepheid period-luminosity zero-point from radial velocities and HIPPARCOS proper motions
Pont, Frederic; Feast, Michael; Whitelock, Patricia
A value for the zero-point (rho) of the Cepheid period-luminosity relation, <M_V>=2.81log P+rho, is deduced by comparing the value of the Oort constant, A, derived from radial velocities with that derived from Hipparcos proper motions. We find in this way that rho=-1.47+/-0.13, in excellent agreement with the value derived from Hipparcos tri…
Infrared spectroscopy of Sakurai's object
Eyres, S. P. S.; Salama, A.; Evans, A. +2 more
We present near (ground-based) and far (ISO) infrared spectroscopy of Sakurai's object. As in the case of the optical spectrum, between 1996 and 1997 April the near-infrared spectrum underwent a dramatic change to later spectral type, and there is some evidence that the spectrum continued to evolve during 1997. Molecular features of carbon-bearing…
The new gravitational lens system B1030+074
Koopmans, L. V. E.; Browne, I. W. A.; Wilkinson, P. N. +6 more
We report the discovery of a new double-image gravitational lens system, B1030+074, which was found during the Jodrell Bank-VLA Astrometric Survey (JVAS). We have collected extensive radio data on the system using the VLA, MERLIN, the EVN and the VLBA, and optical observations using WFPC2 on the HST. The lensed images are separated by 1.56 arcsec …
HST spatially resolved spectra of the accretion disc and gas stream of the nova-like variable UX Ursae Majoris
Horne, Keith; Hubeny, Ivan; Long, Knox S. +3 more
Time-resolved eclipse spectroscopy of the nova-like variable UX UMa obtained with the HST/FOS on 1994 August and November is analysed with eclipse mapping techniques to produce spatially resolved spectra of its accretion disc and gas stream as a function of distance from the disc centre. The inner accretion disc is characterized by a blue continuu…
Deep radio observations of 3C 324 and 3C 368: evidence for jet-cloud interactions
Carilli, C. L.; Garrington, S. T.; Best, P. N. +2 more
High-resolution, deep radio images are presented for two distant radio galaxies, 3C 324 (z=1.206) and 3C 368 (z=1.132), which are both prime examples of the radio-optical alignment effect seen in powerful radio galaxies with redshifts z>~0.6. Radio observations were made using the Very Large Array in A-array configuration at 5 and 8GHz, and usi…
The EC14026 stars - VI. PG1047+003
O'Donoghue, D.; Kilkenny, D.; Lynas-Gray, A. E. +2 more
We report the discovery of rapid oscillations in the sdB star PG1047+003. The oscillations are multiperiodic, with nine periods in the range 104-162s. The optical spectrum of PG1047+003 is consistent with that of a single sdB star. Line profile fitting yields an effective temperature of 35000+/-1000K and log g=5.9+/-0.1, although optical photometr…
On the determination of absolute magnitude zero-points from HIPPARCOS parallaxes
Koen, Chris; Laney, Dave
The period-luminosity (PL) relation zero-point determination from Hipparcos trigonometric parallaxes of Cepheids is contentious. It is shown that the method used by Feast & Catchpole is equivalent to a standard minimization of sum of squares, and that it is free of Lutz-Kelker bias. The same technique is applied to RR Lyrae and field HB star d…
Radio jet interactions in the radio galaxy PKS 2152-699
di Serego Alighieri, S.; Fosbury, R. A. E.; Morganti, R. +3 more
We present radio observations of the radio galaxy PKS 2152-699 obtained with the Australia Telescope Compact Array. The much higher resolution and signal-to-noise ratio of the new radio maps reveal the presence of a bright radio component about 10 arcsec north-east of the nucleus. This lies close to the highly ionized cloud previously studied in t…
Time-dependent structure in ultraviolet absorption lines of the rapid rotators HD 64760 (B0Ib) and HD 93521 (O9.5V)
Massa, D.; Prinja, R. K.; Howarth, Ian D. +5 more
Cross-correlation provides an effective line-averaging function for spectra containing many line features, a result which can be exploited in order to perform time-series and spatial-domain analyses of absorption-line variability in data of (relatively) poor quality. We apply this method to high-resolution IUE spectra. For the known non-radial pul…
Discovery of extended radio emission in the young cluster Wd1
Waters, L. B. F. M.; Steele, I. A.; Fender, R. P. +4 more
We present 10-µm ISO-SWS and Australia Telescope Compact Array observations of the region in the cluster Wd1 in Ara centred on the B[e] star Ara C. An ISO-SWS spectrum reveals emission from highly ionized species in the vicinity of the star, suggesting a secondary source of excitation in the region. We find strong radio emission at both 3.5 …