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Comet P/Encke's Nongravitational Force
A'Hearn, Michael F.; Schleicher, David G.
A nearly direct measurement of the nongravitational force on a cometary nucleus is presented. IUE spectra of comet P/Encke show significant Greenstein effects even when centered on the nucleus. These imply net heliocentric components of outflow of 1.6 and 0.3 km/s for the OH radicals before and after perihelion near r = 0.8 AU. This implies a larg…
Ultraviolet and Radio Flares from UX ARIETIS and HR 1099
Willson, Robert F.; Lang, Kenneth R.
Simultaneous observations of the RS CVn systems UX Ari and HR 1099 with the IUE satellite and the VLA are presented. Flaring activity is observed at ultraviolet wavelengths with the IUE when none is detected at radio wavelengths with the VLA. Radio flares with no detectable ultraviolet activity have also been observed. Thus, flares in the two spec…
Recent Unusual Activity in the Be Star FY Canis Majoris
Peters, Geraldine J.
Unusual activity observed in the circumstelar envelope of FY CMa during April-May, 1987 is reported. Nightly CCD observations from April 16-20 revealed an invariant H-alpha emission feature and a simple absorption profile for He I 6678 with very weak double emission components. Similar observations on May 2, however, showed that the V lobe of the …
Search for Linear Polarization in Gamma-Ray Sources: Possible Evidence for the VELA Pulsar
Caraveo, P. A.; Bignami, G. F.; Mitrofanov, I. +1 more
The use of the azimuthal distribution of planes containing e(+)/e(-) pairs from high-energy photon materialization to investigate the nature of gamma-ray sources is discussed. Analytical work done on COS B data for bright COS B sources (Vela, Crab, and Geminga) and for a reference background region is presented along with results which are indicat…
Ultraviolet Spectroscopy of the ``Jetlike'' Condensations of NGC 4151
Bruhweiler, F. C.; Smith, Andrew M.
The spectrometers aboard the International Ultraviolet Explorer (IUE) are used to obtain UV spectroscopy of the jetlike condensations seen extending 18" from the nucleus of the nearby Seyfert 1 galaxy NGC 4151. New data reduction techniques are used to detect, delineate, and measure weak nebular emission in IUE spectra. Spatially resolved extended…
Voyager and IUE Observations of 3C 273: Detection of Possible Lyman Continuum Absorption in a Nearby (z = 0.158) Quasar
Reichert, G. A.; Carone, T. E.; Wu, C. -C. +1 more
We report results of near-simultaneous IUE and Voyager ultraviolet spectrometer (UVS) observations of 3C 273, obtained during the period of 1985 late July-early August. The data cover a total combined wavelength range 500-3200 A (observed frame). This is the first time that observations shortward of 1200 A have been obtained for any extragalactic …
The X-Ray to Infrared Energy Distribution of the Quasar PG 0026+129
Maraschi, L.; Tanzi, E. G.; Chiappetti, L. +4 more
PG 0026+129 was observed with EXOSAT in 1983 and 1984. No variation between the two epochs was detected. The energy distribution from 0.2 to 6 keV is well fitted by a power law of energy index α = 1.06 +/- 0.25 and with Galactic absorption. Quasi-simultaneous spectrophotometry in the UV and optical range, together with near-infrared photometry was…
IUE Observations of the Dwarf Nova BV Centauri
Hassall, B. J. M.; Wade, Richard A.; Williger, G. +1 more
The IUE observations of the dwarf nova BV Cen in quiescence are summarized. The reprocessed spectra from January 1979 are analyzed to show that the maximum temperature of the white dwarf primary star, based on its brightness at 1375 A, ranges from 42,000 to about 125,000 K depending upon the adopted values of interstellar reddening, the mass of th…
An EXOSAT Observation of CTB 80
Parmar, A. N.; White, N. E.; Angelini, L. +2 more
The results of an EXOSAT observation of the Crab-like supernova remnant CTB 80 are presented. The 0.05-6 keV X-ray spectrum is well fitted by a power law with an energy index of 0.9, similar to that of other Crab-like remnants. This spectral measurement differs from an earlier result from an Einstein observation where a much steeper index was repo…
Massive Star-Formation Regions in the Magellanic Clouds
Thompson, I. B.; Hutchings, J. B.
We present optical and UV spectroscopy of stars from six compact, luminous groups or clusters in the SMC and LMC. The groups are characterized by high concentrations of nebulosity or starlight confined to areas smaller than 30" on a side, in which some stars can be resolved. The spectra and fluxes are used to derive luminosities and effective temp…