Search Publications
First X-ray observations of the polar CE Gru
Cropper, Mark; Ramsay, Gavin
We report the detection of the polar CE Gru in X-rays for the first time. We find evidence for a dip seen in the hard X-ray light curve which we attribute to the accretion stream obscuring the accretion region in the lower hemisphere of the white dwarf. The X-ray spectrum can be fitted using only a shock model: there is no distinct soft X-ray comp…
Radio observations of super star clusters in dwarf starburst galaxies
Forbes, Duncan A.; Stevens, Ian R.; Norris, Ray P.
We present new radio continuum observations of two dwarf starburst galaxies, NGC 3125 and 5408, with observations at 4.80 GHz (6 cm) and 8.64 GHz (3 cm), taken with the Australia Telescope Compact Array (ATCA). Both galaxies show a complex radio morphology with several emission regions, mostly coincident with massive young star clusters. The radio…
Infrared light curves and absolute stellar parameters of the Algol system δ Librae: is δ Librae really an overmassive Algol binary?
Claret, A.; Arevalo, M. J.; Lazaro, C.
We present the first infrared (IR) light curves in the J, H and K bands of δ Lib obtained at different observing runs from 1994 to 1998. These IR light curves, showing a secondary minimum much deeper than in visual bands, have been analysed in order to determine a new set of physical parameters. A new program using the Roche geometry, and stellar …
On the nature of a secondary main-sequence turn-off in the rich LMC cluster NGC 1868
de Grijs, R.; Santiago, B.; Castro, R. +1 more
Evidence for a second main-sequence turn-off in a deep colour-magnitude diagram (CMD) of NGC 1868 is presented. The data were obtained with Hubble Space Telescope (HST) WFPC2 and reach down to m555~= 25 mag. Besides the usual τ~= 0.8 Gyr turn-off found in previous analyses, another possible turn-off is seen at m555~= 21 mag (…
Sub-arcsecond atomic hydrogen absorption in the Seyfert galaxies NGC 7674 and NGC 7469
Beswick, R. J.; Pedlar, A.; McDonald, A. R.
Neutral hydrogen has been studied on sub-arcsecond scales in two Seyfert galaxies, NGC 7469 and NGC 7674. The 1.4-GHz continuum emission from these sources agree with higher frequency measurements and shows linear, triple source in NGC 7674 and a compact source surrounded by a weak ring of radio emission in NGC 7469. In both of these sources we de…
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…
Observations of Hipparcos short-period red giant stars
Koen, Chris; van Wyk, Francois; Laney, Dave
Optical UBV(RI)C and infrared JHK photometry is presented of a small sample of giant stars with short periods in the Hipparcos catalogue. Observations were limited, but were sufficient to rule out most of the Hipparcos periods. Radial velocity measurement were also made for a few stars, over six successive nights. Low-level variability …
On the kinematic deconvolution of the local neighbourhood luminosity function
Siebert, A.; Pichon, C.; Bienaymé, O.
A method for inverting the statistical star counts equation, including proper motions, is presented; in order to break the degeneracy in that equation, it uses the supplementary constraints required by dynamical consistency. The inversion gives access to both the kinematics and the luminosity function of each population in three régimes: the singu…
Contribution to the search for binaries among Am stars - III. HD 7119: a double-lined spectroscopic binary and a triple system
Udry, S.; Ginestet, N.; Prieur, J. -L. +1 more
Radial velocity observations of HD 7119 with the CORAVEL instrument at Observatoire de Haute-Provence are reported. Known as an Amδδ Del metallic-line star, HD 7119 was included in our spectroscopic survey of Am-type stars, the purpose of which was to determine the frequency of binaries in this stellar family. This object is found to be a double-l…
The galaxy population of Cl1601+42 at
Fransson, Claes; Dahlén, Tomas; Näslund, Magnus
Photometric redshifts are used to determine the rest-frame luminosity function (LF) of both early- and late-type galaxies to for the cluster Cl1601+42 at . The total LF shows a steep faint-end slope , indicating the existence of a population of numerous dwarf galaxies. Luminous galaxies, with are mostly red, early-type galaxies, with a LF best des…