Search Publications
The birth of a planetary nebula around the carbon star IRC+10216
Meixner, M.; Skinner, C. J.; Bobrowsky, M.
Our current understanding of the evolution of solar-type stars suggests that after a period as a red giant star, during which mass loss occurs continuously in the form of a stellar wind, a period of intense mass loss known as a superwind occurs, during which a significant fraction of the envelope of the star is ejected into space, forming the mate…
The complex gravitational lens system B1933+503
Pearson, T. J.; Bremer, M.; Blandford, R. D. +15 more
We report the discovery of the most complex arcsec-scale radio gravitational lens system yet known. B1933+503 was found during the course of the CLASS survey and MERLIN and VLA radio maps reveal up to 10 components. Four of these are compact and have flat spectra; the rest are more extended and have steep spectra. The background lensed object appe…
A complete infrared Einstein ring in the gravitational lens system B1938+666.
Blandford, R. D.; Bremer, M. N.; Jackson, N. +7 more
We report the discovery, using NICMOS on the Hubble Space Telescope, of an arcsec-diameter Einstein ring in the gravitational lens system B1938 +666. The lensing galaxy is also detected, and is most likely an early-type galaxy. Modelling of the ring is presented and compared with the radio structure from MERLIN maps. We show that the Einstein ring…
B0712+472: a new radio four-image gravitational lens
Muxlow, T. W. B.; Pearson, T. J.; Bremer, M. +14 more
A new four-image gravitational lens system, B0712+472, has been discovered during the Cosmic Lens All-Sky Survey. This system consists of four flat-spectrum radio images that are also seen on a Hubble Space Telescope (HST) image, together with the lensing galaxy. We present MERLIN, VLA and VLBA maps and WHT spectra of the system as well as the HST…
The equatorial disc of the Be star X Persei
Waters, L. B. F. M.; de Martino, D.; Boogert, A. C. A. +4 more
We study the long-term behaviour of the equatorial disc of the Be/X-ray binary X Persei (X Per), combining new low-resolution IUE spectra and IR photometry with UV, optical and IR observations collected from the literature. We find that the near-UV continuum level of X Per varies along with the optical brightness. From the UV observations, we also…
Non-parametric reconstruction of cluster mass distribution from strong lensing: modelling Abell 370.
Saha, Prasenjit; Williams, Liliya L. R.; Abdelsalam, Hanadi M.
The authors describe a new non-parametric technique for reconstructing the mass distribution in galaxy clusters with strong lensing, i.e. from multiple images of background galaxies. The observed positions and redshifts of the images are considered as rigid constraints, and through the lens (ray-trace) equation they provide us with linear constrai…
Nuclear stellar discs in early-type galaxies - II. Photometric properties
van den Bosch, Frank C.; Scorza, Cecilia
Hubble Space Telescope images of two early-type galaxies harbouring both nuclear and outer stellar discs are studied in detail. By means of a photometric decomposition, the images of NGC 4342 and 4570 are analysed and the photometric properties of the nuclear discs investigated. We find a continuity of properties in the parameter space defined by …
The EC 14026 stars - VII. PG 1605+072, a star with many pulsation modes
O'Donoghue, D.; Kilkenny, D.; Lynas-Gray, A. E. +3 more
We report the discovery of large-amplitude (~0.25 mag) pulsations in the bright (V=12.8) sdB star, PG 1605+072. The dominant period is 480s, but more than 20 periods were present on at least three separate occasions. Frequency analysis of the complete data set yields more than 30 periods. A few of these are harmonics or linear combinations of the …
Spectroscopic confirmation of redshifts predicted by gravitational lensing
Ellis, Richard; Smail, Ian; Kneib, Jean-Paul +4 more
We present deep spectroscopic measurements of 18 distant field galaxies identified as gravitationally lensed arcs in a Hubble Space Telescope image of the cluster Abell2218. Redshifts of these objects were predicted by Kneib et al. using a lensing analysis constrained by the properties of two bright arcs of known redshift and other multiply imaged…
The 1996 outburst of GRO J1655-40: the challenge of interpreting the multiwavelength spectra
Horne, Keith; Shrader, C. R.; O'Brien, K. +6 more
We report on the results of a multiwavelength campaign to observe the soft X-ray transient (SXT) and superluminal jet source GRO J1655-40 in outburst using HSTRXTECGRO together with ground-based facilities. This outburst was qualitatively quite different from other SXT outbursts and from previous outbursts of this source. The onset of hard X-ray a…