Search Publications
A multiwavelength view at the heart of the superwind in NGC253
Forbes, Duncan A.; Brodie, Jean P.; Stevens, Ian R. +2 more
Although NGC253 is one of the nearest starburst galaxies, the activity in its central regions is yet to be fully understood. Here we present new optical data from the Hubble Space Telescope of its central region, which reveal numerous discrete sources in a ring-like structure. This is combined with data at infrared, millimetre, radio and X-ray wav…
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…
Highly polarized structures in the near-nuclear regions of Cygnus A: intrinsic anisotropy within the cones?
Tadhunter, C. N.; Packham, C.; Sparks, W. +6 more
We present near-infrared imaging polarimetry observations of the nucleus of Cygnus A (z= 0.0567), taken with the NICMOS camera of the Hubble Space Telescope (HST) at a wavelength of 2.0µm. These maps reveal a highly collimated region of polarized emission straddling the nucleus and extending to a radius of 1.2arcsec. Remarkably, this feature…
Imaging of the protoelliptical NGC 1700 and its globular cluster system
Forbes, Duncan A.; Brodie, Jean P.; Kissler-Patig, Markus +1 more
An excellent candidate for a young elliptical, or `protoelliptical' galaxy is NGC 1700. Here we present new B-, V- and I-band imaging using the Keck telescope, and reanalyse existing V- and I-band images from the Hubble Space Telescope. After subtracting a model of the galaxy from the Keck images, NGC 1700 reveals two symmetric tidal tail-like str…
A photometric and spectroscopic study of the brightest northern Cepheids - III. A high-resolution view of Cepheid atmospheres
Vinkó, József; Kiss, László L.
We present new high-resolution spectroscopic observations (λ/Δλ~40000) of 18 bright northern Cepheids carried out at the David Dunlap Observatory in 1997. The measurements mainly extend those presented in Paper I of this series, adding three more stars (AW Per, SV Vul, T Mon). The spectra were obtained in the yellow-red spectral region in the inte…
The hyperluminous infrared quasar 3C 318 and its implications for interpreting submm detections of high-redshift radio galaxies
Willott, Chris J.; Rawlings, Steve; Jarvis, Matt J.
We present near-infrared spectroscopy and imaging of the compact steep-spectrum radio source 3C 318, which shows it to be a quasar at redshift z=1.574 (the z=0.752 value previously reported is incorrect). 3C 318 is an IRAS, ISO and SCUBA source so its new redshift makes it the most intrinsically luminous far-infrared (FIR) source in the 3C catalog…
A study of interstellar Nai D absorption lines towards the Lupus molecular clouds
Crawford, I. A.
Intermediate-resolution (60000<=R<=120000) observations of interstellar Nai lines towards 29 stars in the general direction of the Lupus molecular clouds (330°<~l<~350° 0°<~b<~25°) are presented. Previously published spectra towards an additional seven stars are also included. Based on the Hipparcos distances to these stars, and …
Time evolution of galactic warps in prolate haloes
Ideta, M.; Hozumi, S.; Tsuchiya, T. +1 more
A recent observation with the Hipparcos satellite and some numerical simulations imply that the interaction between an oblate halo and a disc is inappropriate for the persistence of galactic warps. Following on from this, we have compared the time evolution of galactic warps in a prolate halo with that in an oblate halo. The haloes were approximat…
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…
Dynamic-range limitations of intensified CCD photon-counting detectors
Fordham, J. L. A.; Moorhead, C. F.; Galbraith, R. F.
The bright limit to the dynamic range of intensified CCD photon-counting detectors is governed by coincidence losses. In this paper a theoretical analysis of the loss mechanisms is carried out and verified using laboratory data. For applications where the input source is stable, such as star field imaging from space, the theoretical dynamic-range …