Search Publications
Optical observations of the hot post-asymptotic giant branch star, HD 177566.
Dufton, P. L.; Keenan, F. P.; Kendall, T. R. +2 more
An LTE model atmosphere analysis of optical and ultra-violet spectra is presented for a hot high galactic latitude star, HD 177566, previously identified as a post-asymptotic giant branch candidate from its ultra-violet spectrum. The derived atmospheric parameters and chemical composition confirm that HD 177566 is a low mass (M=~0.55Msun
The Linear Polarization of 3C 345 in the Ultraviolet
Boyd, Patricia T.; Impey, C. D.; Nelson, M. J. +9 more
The linear polarization of 3C 345, a superluminal radio source and OVV quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 A and 2770 A) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the UV (p > 5%). Ground-based polarimetry was obtained 11 days late…
HST observations of Cygnus A: circumnuclear effects of a powerful jet ?
Sparks, W. B.; Macchetto, F.; Miley, G. K. +1 more
We present 340nm continuum and [OII] line images of the nuclear region of the radio galaxy Cygnus A at 0".1 resolution. At this high resolution the northwestern of the two nuclear components is resolved into two separate, line emitting subcomponents, and the radio jet points accurately between them. This suggests that the radio jet has blasted a p…
Optical and UV spectroscopy towards stars in the direction of the Cohen high-velocity H I stream.
Dufton, P. L.; Keenan, F. P.; Bates, B. +2 more
We present high-resolution, high signal-to-noise ratio optical spectra and UV spectra obtained with lUE for several stars that lie within and adjacent to the Cohen high- velocity (Hv) stream, which is considered by Cohen to lie within 300 pc. From spectral classifications, published photometry and LTE model atmosphere analysis of our stellar spect…
A non-thermal radio/optical/X-ray source in PKS 2316-423.
Fabian, A. C.; Crawford, C. S.
We report observations of PKS 2316-423 in the ultraviolet and with the ROSAT HRI, where it appears as a bright point source. Optical spectroscopy reveals weak emission lines and a strong, excess blue continuum that is centrally concentrated. The combined optical- ultraviolet continuum spectrum cannot be fitted by any simple combination of a main-s…
HST observations of the core of globular cluster NGC 6397
Boksenberg, A.; Burgarella, D.; Barbieri, C. +17 more
The core of the nearby and very concentrated globular cluster NGC 6397 has been imaged through the f/96-F140W, f/48-F140W, f/96-F210M, and f/48-F220W ultraviolet filters of the Faint Object Camera on board the Hubble Space Telescope down to an ultraviolet limiting magnitude of ~19. The most interesting objects in the field of view are six very bri…
UV variability of IRAS 13224-3809, a rapidly X-ray variable far-infrared luminous galaxy.
Mas-Hesse, J. M.; Boller, Th.; Rodriguez-Pascual, P. M. +1 more
We have detected strong Lyα line variability in IRAS 13224-3809, a very luminous IRAS galaxy known to be a strong and rapidly variable soft X-ray emitter. While a relatively broad Lyα component (FWHM ~ 5000 km/s) remains essentially constant along three IUE observations performed between January and May 1993, the initially strong narrow core compo…
Orbits of Six Visual Double Stars
Docobo, J. A.; Ling, J. F.; Prieto, C.
New orbits have been calculated for the visual double stars WDS 04262N3443, WDS 07573N0108, WDS 08214S0136, WDS 08267N2433, WDS 19549N5049, and WDS 20232N2052 using recent observations. Dynamic parallaxes and masses have been calculated.
On Planetary-Nebula Nuclei of the Spectral Type `Continuous'
Feibelman, Walter A.
A detailed reexamination of existing and new IUE low- and high-resolution spectra, plus a search of recent literature, shows that for most of the central stars of planetary nebulae the spectral classification previously called "continuous type" does not really exist. The stellar continua show primarily photospheric absorption features of N V, O V,…
Gamma Rays from the Geminga Pulsar: Variations with Time and Phase
Grenier, I. A.; Hermsen, W.; Bennett, K. +5 more
Pulsed gamma radiation from the Geminga pulsar was recorded by the COS B satellite from 50 MeV to 5 GeV between 1975 and 1982. It has been analyzed to derive the source spectral properties as a function of time and phase. The two main peaks are separated by 0.50 +/- 0.01 in phase. Significant pulsed emission has also been detected in both phase re…