Search Publications
An infrared image of the dust disc around beta PIC
Walker, H. J.; Lemke, D.; Klaas, U. +2 more
The star beta Pictoris is a normal main-sequence star with a remnant disc of cool dust around it. We present observations of the beta Pic dust disc in the far-infrared, obtained using the photometer (ISOPHOT) on the Infrared Space Observatory (ISO) satellite. We resolve the edge-on disc using high-resolution scans, with full widths at half-maximum…
UBV photometry, UV spectroscopy and radio observations of the peculiar binary V Sagittae
Eyres, S. P. S.; Naylor, T.; Wood, Janet H. +2 more
We have performed high-speed UBV photometric observations on the peculiar binary V Sagittae. Using three new eclipse timings we update the orbital ephemeris and convert it to a dynamical time-scale (TDB). We also searched for quasi-periodic oscillations but did not detect them. Using the Wilson-Devinney algorithm we have modelled the light curve t…
Abundances of metal-weak thick-disc candidates
Bonifacio, P.; Molaro, P.; Centurion, M.
High-resolution spectra of five candidate metal-weak thick-disc stars suggested by Beers & Sommer-Larsen are analysed to determine their chemical abundances. The low abundance of all the objects has been confirmed, with metallicity reaching [Fe/H]=-2.9. However, for three objects the astrometric data from the Hipparcos catalogue suggest they a…
Infrared spectroscopy of Nova Cassiopeiae 1993 - III. ISO observations
Eyres, S. P. S.; Salama, A.; Evans, A. +2 more
The [Oiv]lambda25.89 fine-structure line has been detected in Nova Cassiopeiae 1993 (V705 Cas) by the Short Wavelength Spectrometer on the Infrared Space Observatory (ISO). Preliminary analysis using cloudy suggests that oxygen is overabundant relative to solar by at least 25 (by number), and that the abundance of neon is 0.5 x solar at most; the …
Analysis of the oscillations in HST observations of the quiescent SU UMa type dwarf nova WZ Sagittae
Horne, Keith; Wood, Janet H.; Welsh, William F. +2 more
An analysis of the UV oscillations in WZ Sge is presented, in which we obtain the oscillation amplitude spectra. We find a strong 27.9-s oscillation in our Hubble Space Telescope (HST) UV and zeroth-order light curves as well as weaker oscillations at 28.4s in the UV and 29.1s in the zeroth order. We find that the main oscillation amplitude spectr…
Radio-optical alignments in a low radio luminosity sample
Rawlings, Steve; Lacy, Mark; Ridgway, Susan E. +2 more
We present an optically based study of the alignment between the radio axes and the optical major axes of eight z~0.7 radio galaxies in a 7C sample. The radio galaxies in this sample are ~20 times less radio-luminous than 3C galaxies at the same redshift, and are significantly less radio-luminous than any other well-defined samples studied to date…
Hubble Space Telescope observations of the black hole X-ray transient GRO J0422+32 near quiescence
Haswell, C. A.; Hynes, R. I.
We present HST/FOS ultraviolet and optical spectroscopy of the black hole X-ray transient GRO J0422+32 shortly before the system reached quiescence. We find that the accretion spectrum from 2500 to 9000 A can be very well fitted by a self-absorbed synchrotron model, with superposed H I and Mg II emission lines. The explanations that we suggest for…
Unbiased image reconstruction as an inverse problem
Pijpers, F. P.
An unbiased method for improving the resolution of astronomical images is presented. The strategy at the core of this method is to establish a linear transformation between the recorded image and an improved image at some desirable resolution. In order to establish this transformation only the actual point spread function and a desired point sprea…
Spiral galaxy distance indicators based on near-infrared photometry
de Grijs, Richard; Peletier, Reynier F.
We compare two methods of distance determination to spiral galaxies using optical/near-infrared (NIR) observations, the (I-K) versus MK colour-absolute magnitude (CM) relation and the I- and K-band Tully-Fisher relation (TFR). Dust-free colours and NIR absolute magnitudes greatly enhance the usefulness of the NIR CM relation as a distan…
Segregated optical-near-infrared colour distributions of Medium Deep Survey galaxies
Benitez, N.; Ferreras, I.; Martinez-Gonzalez, E. +1 more
We present a K survey of 29 fields covering approximately 90 arcmin^2 from the Medium Deep Survey (MDS) catalogue down to a completeness magnitude of K=18.0 (limiting magnitude K=19.0). The morphology obtained by the MDS team using high-resolution images from HST/WFPC2 along with our near-infrared (NIR) observations allows colour-magnitude and col…