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The early-type binary KX Velorum.

Drechsel, H.; Lorenz, R.; Mayer, P.

A spectroscopic study of the double-lined OB-type binary system KX Vel is presented. Radial velocities were measured on 20 new CCD spectra and 4 high dispersion IUE SWP images. From a combination with early photographic data, the orbital period was found to be 26.306d. The high precision radial velocity curve of the evolved primary component allow…

Ongoing Mass Ejection in the Peculiar, Hot Do Degenerate KPD 0005+5106

Sion, Edward M.; Barstow, Martin A.; Holberg, Jay B. +1 more

We present an analysis of four high-resolution far-ultraviolet spectra of the hot, peculiar DO white dwarf KPD 0005+5106 obtained with short-wavelength prime (SWP) spectrograph aboard the International Ultraviolet Explorer (lUE) spacecraft. These spectra reveal weak, probably variable, peculiar absorption and emission transitions of ultrahigh exci…

An Explanation of the ROSAT High-Resolution Imager Ultraviolet Sensitivity

Murray, S. S.; Barbera, M.; Collura, A. +1 more

The UV sensitivity to bright stars observed during operations of the high-resolution imager (HRI) on the X-ray-XUV Roentgen Satellite (ROSAT) has been commonly interpreted as a result of enhanced transmission solely in the wavelength range 1500-1700 Å of the HRI's UV/ion shield. We report on recent laboratory UV transmission measurements of HRI fl…

3C 254: the alignment effect and unification schemes

Bremer, M. N.

3C 254 is a radio-loud quasar at z=0.734. Optical line and continuum emission from the underlying galaxy is clearly extended and aligned with the radio axis; the object shows the so-called `alignment effect' which is often seen in powerful radio galaxies. This is the clearest case yet of the continuum alignment effect in a radio-loud quasar. The o…

Optical and UV observations of the BL Lacertae object PKS 2155-304.

Wagner, S. J.; Heidt, J.; Wilhelm-Erkens, U.

The BL Lac object PKS 2155-304 has been monitored in two subsequent observing campaigns within three weeks in June 1990 and during another run in September 1994 at optical wavelengths. During the first part PKS 2155-304 showed night-to-night variations of a few percent, whereas in the second part no variability could be detected. During the third …

NOTE: Saturn Ring-Plane Crossing, May 1995: Pole Precession and Ring Thickness

Bosh, Amanda S.; Rivkin, Andrew S.; Percival, Jeffrey W. +2 more

On 22 May 1995, as the Earth crossed through Saturn's ring-plane, we used the Wide Field Planetary Camera 2 on the Hubble Space Telescope to image Saturn and its rings for 10 hr centered near the predicted time of ring-plane crossing. By performing photometry on the rings, we find that the time of ring-plane crossing is later than the nominal pred…

Infrared Space Observatory Mapping of 60 Micron Dust Emission around Vega-Type Systems

Stencel, R. E.; Backman, D. E.; Fajardo-Acosta, S. B.

We mapped 60 µm emission around five Vega-type systems. We utilized the PHOT-C100 far-infrared array camera on board the Infrared Space Observatory. The spatial resolution of the maps is ~30". The maps of three sources (α CrB, σ Her, and α Cen) do not show any evidence of extended emission. The map of γ Oph shows marginal hints of extended e…

A spectral analysis of HDE 269445 from optical and infrared observations.

Schmutz, W.; Nota, A.; Origlia, L. +1 more

We present new, near-IR spectroscopic observations of HDE 269445, which we combine with published HST and IUE ultraviolet data and optical high resolution spectra. We discuss the spectral morphology of the star from UV to near-IR wavelengths, concentrating on profile variations in the UV and optical H and He lines. From a spectroscopic analysis wi…

The changes in the UV emission lines of RR Telescopii from 1978 to 1993. I. The IUE SWP region

Hack, M.; Selvelli, P.; Zuccolo, R.

Line emission intensities and FWHMs in the range 1175-1900 Angstroms have been measured on high resolution IUE spectra of RR Tel taken from 1978 to 1993. The variations observed in the emission line intensities show a rather strong correlation with the line ionization. The decrease is of a factor larger than three and up to ten for the low-ionizat…

Hubble Space Telescope Observations of Nebular Morphologies and Their Implications

Livio, Mario