Search Publications
The discovery of photospheric nickel in the hot DO white dwarf REJ 0503-289
Werner, K.; Dreizler, S.; Barstow, M. A. +4 more
We present the first evidence for the direct detection of nickel in the photosphere of the hot DO white dwarf REJ 0503-289. While this element has been seen previously in the atmospheres of hot H-rich white dwarfs, this is one of the first similar discoveries in a He-rich object. Intriguingly, iron, which is observed to be more abundant than Ni in…
Lyα imaging of a very luminous z=2.3 starburst galaxy with WFPC2
Roche, Nathan; Lowenthal, James; Woodgate, Bruce
We investigate the Lyα and UV continuum morphology of one of the most luminous known Lymanα emitting galaxies (the `Coup Fourré Galaxy'), associated with a z=2.3 damped Lyα absorption system in the spectrum of the QSO PHL 957. The galaxy is observed with the Hubble Space Telescope Wide-Field Planetary Camera 2 (HST WFPC2), through a narrow filter …
Hubble Space Telescope imaging survey of sub-mJy star-forming galaxies - I. Morphologies at z~0.2
Mobasher, Bahram; Serjeant, Stephen; Oliver, Seb +1 more
We present the first results of our Hubble Space Telescope HST WFPC2 F814W snapshot imaging survey, targeting virtually all sub-mJy decimetric radio-selected star-forming galaxies. The radio selection at ~1GHz is free from extinction effects and the radio luminosities are largely unaffected by AGN contamination, making these galaxies ideal tracers…
UV spectroscopy of the peculiar binary V Sagittae in a low state
Wood, Janet H.; Lockley, J. J.
In this paper we present the first phase-resolved, high-resolution, UV spectroscopy of V Sge. HST GHRS observations were obtained covering 1.5 orbital cycles of V Sge in a low state. We covered the Heii 1640 line and the Civ 1550 doublet alternately, and also obtained one spectrum covering Mgii 2800. We create continuum and line flux light curves …
Interstellar CO towards X Persei (HD 24534) - II. Two-component model
Kaczmarczyk, Grzegorz
The observations made by the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope (HST) of molecular CO in absorbing gas towards X Persei are reported. The two-component statistical equilibrium model incorporating radiative excitation of CO by line emission at the same velocity that originates in nearby molecular clouds ha…
Morphological number counts and redshift distributions to I=25 from the Hubble Deep Fields: constraints on cosmological models from early-type galaxies
Couch, Warrick J.; Phillipps, S.; Driver, S. P. +5 more
We combine magnitude and photometric redshift data on galaxies in the Hubble Deep Fields with morphological classifications in order to separate out the distributions for early-type galaxies. The updated morphological galaxy number counts down to I=25 and the corresponding redshift distributions are used as joint constraints on cosmological models…
The region of Collinder 121
Kaltcheva, N. T.
The distribution of bright B-type stars in a field with a radius of 5° centred at the Galactic open cluster Cr 121 is studied utilizing Strömgren and Hβ photometry. All PPM stars earlier than spectral type A0 are used, revealing a loose nearby structure at a distance of 660-730pc, and a compact more distant group, which appears to be a genuine clu…
Near-infrared adaptive optics imaging of nuclear spiral structure in the Seyfert galaxy NGC 3227
Morris, Simon L.; Chapman, Scott C.; Walker, Gordon A. H.
We present high spatial resolution, near-infrared images in J, H and K of the nucleus of NGC 3227, obtained with the Adaptive Optics Bonnette on the Canada-France-Hawaii Telescope. The ~0.15arcsec (17pc) resolution allows structures to be probed in the core region. Dust obscuration becomes significantly less pronounced at longer wavelengths, revea…
Optical, X-ray and radio observations of HD 61396: a probable new RS CVn-type binary
Singh, K. P.; Drake, S. A.; Pandey, S. K. +1 more
We have carried out BVR photometric and Hα spectroscopic observations of the star HD 61396 during 1998 March 20 to 1999 April 3. We have discovered regular optical photometric variability from this star, with an inferred period of 31.95+/-0.10d, and an amplitude of ~0.18mag. A possible period of 35.34+/-0.12d, as determined with Hipparcos, cannot …
The space density of low-redshift active galactic nuclei
Boyle, B. J.; Londish, D.; Schade, D. J.
We present a new determination of the optical luminosity function (OLF) of active galactic nuclei (AGN) at low redshifts (z<0.15) based on Hubble Space Telescope (HST) observations of X-ray-selected AGN. The HST observations have allowed us to derive a true nuclear luminosity function for these AGN. The resulting OLF illustrates a two power-law…