Search Publications
The timing properties of Sco X-1 along its Z track with EXOSAT
van der Klis, Michiel; Dieters, Stefan W.
We present a systematic, homogeneous analysis of all the EXOSAT ME, high time resolution data on Sco X-1. We investigate, for the first time, all power spectral properties of the <100Hz quasi-periodic oscillations (QPO) and noise of Sco X-1 as a function of position on the Z-shaped track traced out in the X-ray colour-colour diagram. For this p…
NICMOS images of JVAS/CLASS gravitational lens systems
Jackson, N.; Browne, I. W. A.; Xanthopoulos, E.
We present Hubble Space Telescope (HST) infrared images of four gravitational lens systems from the JVAS/CLASS gravitational lens survey and compare the new infrared HST pictures with previously published WFPC2 HST optical images and radio maps. Apart from the wealth of information that we get from the flux ratios and accurate positions and separa…
The evolution of 3CR radio galaxies from z1
McLure, R. J.; Dunlop, J. S.
We present the results of a comprehensive re-analysis of the images of a virtually complete sample of 28 powerful 3CR radio galaxies with redshifts 0.6<z<1.8 from the Hubble Space Telescope (HST) archive. Using a two-dimensional modelling technique we have derived scalelengths and absolute magnitudes for a total of 16 3CR galaxies with a med…
Rapidly oscillating M giant stars?
Koen, Chris; Laney, Dave
The Hipparcos mission discovered a few dozen M giant stars with periods P shorter than 10d. Similar stars may be found in other large data bases of new variables (e.g., OGLE). The three possible sources of the magnitude variations - pulsation, starspots and ellipsoidal deformation - are discussed in general terms. The parallaxes and V-I colour ind…
Testing the photoionization models of powerful radio galaxies: mixed line-emitting media in 3C 321
Tadhunter, C. N.; Axon, D. J.; Robinson, A. +1 more
The photoionization models for the narrow emission-line regions of powerful radio galaxies have yet to be tested in depth. To this end, we present high-quality long-slit spectroscopy of the powerful double-nucleus radio galaxy 3C 321. The data have good enough spatial resolution to be able to trace the variation in emission-line properties on kpc …
The optical spectrum of the planetary nebula NGC 6543
Feibelman, W. A.; de Koter, A.; Hyung, S. +2 more
With the Hamilton echelle spectrograph at the Lick Observatory, emission-rich spectral lines of the planetary nebula NGC 6543 were secured in the wavelength range from 3550 to 10100Å. We chose two bright regions, ~8arcsec east and ~13arcsec north of the central star, the physical conditions and chemical abundances of which may differ as a result o…
Low-mass spectroscopic binaries in the Hyades: a candidate brown dwarf companion
Reid, I. Neill; Mahoney, S.
We have used the HIRES echelle spectrograph on the Keck I telescope to obtain high-resolution spectroscopy of 51 late-type M dwarfs in the Hyades cluster. Cross-correlating the calibrated data against spectra of white dwarfs allows us to determine heliocentric velocities with an accuracy of +/-0.3kms-1. 27 stars were observed at two epo…
OB association members in the ACT and TRC catalogues
Hoogerwerf, Ronnie
The Hipparcos Catalogue contains members of nearby OB associations brighter than 12th magnitude in V. However, membership lists are complete only to magnitude V=7.3. In this paper we discuss whether proper motions listed in the `Astrographic Catalogue+Tycho' reference catalogue (ACT) and the Tycho Reference Catalogue (TRC), which are complete to V…
A 500kms-1 outflow from the young bipolar planetary nebula Mz 3
Redman, M. P.; Meaburn, J.; Holloway, A. J. +2 more
We report the discovery of a pair of hypersonic (~=+/-500kms-1) velocity features located along the bipolar axis of the young planetary nebula Mz 3. The possible physical mechanisms that can produce such extreme outflows are briefly discussed and compared with mechanisms thought to operate in MyCn 18, He 2-111 and KjPn 8, all of which e…
Young massive star clusters in M51
Larsen, Søren S.
A search for young massive star clusters (YMCs) in the nearby face-on spiral galaxy M51 (NGC 5194) has been carried out using UBV CCD images from the prime focus camera on the Lick 3-m Shane telescope. The YMC population is found to be quite rich with a specific U-band luminosity TL(U)~1.4, consistent with the high current star formatio…