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Hubble Space Telescope Observations of Planetary Nebulae in the Magellanic Clouds. I. The Extreme Type I SMP 83/WS 35
Dopita, Michael A.; Ford, Holland C.; Evans, Ian N. +2 more
We have obtained Hubble Space Telescope Planetary Camera images in both the Hα and the [O III] λ5007 emission lines of the planetary nebula SMP 83 alias WS35, alias N66 in the Large Magellanic Cloud. By combining these results with optical and UV spectrophotometry, absolute flux measurements, and dynamical and density information, we have been abl…
A Giant X-Ray Flare on lambda Eridani (B2e)
Smith, Myron A.; Peters, Geraldine J.; Grady, Carol A. +1 more
A 30 ks observation with the ROSAT PSPC distributed over 39 hr shows that the putatively single, mild B2e star Lambda Eri emits at most times a soft X-ray flux at a rate and temperature consistent with other B stars. However, during the middle of our observations, this star's X-ray flux increased by a factor of 6 before returning to the basal leve…
The Ultraviolet Continua of Blazars: A Reconsideration of IUE Archives
Pian, E.; Treves, A.
The IUE archive data on blazars are reconsidered. They refer to 47 objects, 24 radio-strong BL Lac objects, 15 radio-weak BL Lac objects, and eight optically violently variable quasars, increasing substantially the sample examined by Ghisellini et al. (1986). For each object a dereddened spectral slope is evaluated starting from the extraction of …
Time-Series Observations of O Stars. III. IUE and HST Spectroscopy of zeta Ophiuchi and Implications for the ``Photospheric Connection''
Ebbets, D. C.; Bolton, C. T.; Prinja, R. K. +9 more
Stellar-wind variability in the archetypal nonradially pulsating O star ζ Oph (09.5 V) is discussed on the basis of new time-series lUE and HST spectroscopy and archival results. Time-variable "discrete absorption components" are first observed at high velocities (≳ 103 km s-1 ≃ 0.8υ∞) and then migrate blueward; th…
On the Interpretation of the Ultraviolet Spectra of Symbiotic Stars and Recurrent Novae. I.
Shore, Steven N.; Aufdenberg, Jason P.
We present an analysis of high-resolution spectra of several symbiotics and symbiotic novae. We show that the emission lines are severely affected by differential extinction caused by absorption lines in the wind of the red giant companion. The major source of the absorbing spectrum is the forest of lines produced by neutral and singly ionized iro…
NGC 4313. II. Hubble Space Telescope I-Band Surface Photometry of the Nuclear Region
Benedict, G. F.; Franz, O. G.; Hemenway, P. D. +11 more
We present a Hubble Space Telescope I-band Planetary Camera image of the nuclear region of NGC 4314. This is an anemic barred galaxy with recent star formation confined to a nuclear ring. These data resolve the nuclear ring into multiple sites of new star formation and resolve associated dust lanes into discrete clouds. Unsharp masking of a Lucy-R…
H-alpha interferometric, optical and near IR photometric studies of star forming regions. I. The Cepheus B/Sh2-155/Cepheus OB3 association complex.
Wagner, S.; Moreno-Corral, M. A.; C., Chavarria-K. +1 more
Here we report the results of a near IR photo- metric study of about 40 stars of the Cepheus OB3 association (subpopulations a and b), of an attempt to detect near IR counterparts of the discrete radio continuum sources reported by Felli et al. (1978), and of the nature of the IR source AFGL 3000. We also give the results of a Hα interferometric, …
Simultaneous ROSAT, GINGA, VLA, IUE, and Optical Observations of the Bright Quasar H1821+643
Filippenko, Alexei V.; Halpern, Jules P.; Fink, Henner H. +3 more
We report on the first simultaneous optical, UV, and X-ray spectroscopy of the low-redshift (z = 0.297), high-luminosity QSO H 1821 + 643. This multiwavelength campaign was complemented by optical imaging and radio mapping with the VLA. Although there was no significant variability during the 40 day monitoring period in either the UV or X-ray band…
Multifrequency Observations of the Optically Active Radio-quiet Quasar GQ Comae. II. Ultraviolet, Optical, and Infrared Continuum Variability
Sitko, Michael L.; Szczerba, R.; Siemiginowska, Aneta +1 more
This paper summarizes the data and preliminary results of a 3 yr long project to monitor the continuum variability of GQ Comae (PG 1202+281) from 0.12 microns to 3.5 microns. Substantial variability in the optical/ultraviolet flux was observed. The variability is examined using a geometrically thin accretion disk model. The model is able to reprod…
Pickup water group ions at comet Grigg-Skjellerup
Coates, A. J.; Winningham, J. D.; Borg, H. +9 more
The density and velocity distribution of cometary water group ions was measured by the Giotto spacecraft in the regions upstream and downstream of the ‘bow shock’ at comet Grigg-Skjellerup. The results show that the distributions of ions are ring-like until quite close to the shock, the timescales for pitch angle and energy diffusion appear simila…