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Ultraviolet and Visible Spectropolarimetry of the Red Rectangle and HD 44179
Sitko, Michael L.; Reese, Marty D.
We present the first ultraviolet and visible spectropolarimetry of the biconical nebula the Red Rectangle and its associated binary HD 44179. These observations were made between 1992 November and 1995 November using the Faint Object Spectrograph on board the Hubble Space Telescope and two separate ground-based observations. These new data gives m…
The Abell 35 Nebula Inside Out
Feibelman, W. A.; Hollis, J. M.; Pedelty, J. A. +3 more
We present deep 6 cm continuum and narrowband optical emission-line images in Hα λ6563, [O III] λ5007, [O II] λ3727, and [N II] λ6584 of the Abell 35 planetary nebula (PN), showing its unique features. First, surrounding the central binary system, there is a bow shock, best seen predominantly in [O III], possibly weakly in Hα, and not at all in [O…
The Soft and Medium-Energy X-Ray Variability of NGC 5548: A Reanalysis of EXOSAT Observations
Tagliaferri, G.; Stella, L.; Treves, A. +2 more
We present a detailed cross-correlation (CCF) and power spectrum reanalysis of the X-ray light curves of the bright Seyfert 1 galaxy NGC 5548 obtained with EXOSAT. The 0.05-2 keV and 1-4 keV light curves are cross-correlated with the 1-9 keV and 4-9 keV light curves, respectively. We discuss how spurious time lags can be introduced by systematic e…
Modeling Emission Lines from Dwarf Novae in Quiescence
Kallman, Timothy R.; Lee, Y. Paul; Ko, Yuan-Kuen +1 more
For cataclysmic variables with disk accretion, it is plausible that X-rays/extreme-ultraviolet (EUV) radiation as a result of accretion can back-illuminate the accretion disk. Such illumination will photoionize and heat up the disk to form a temperature-inverted layer in which emission lines can form. We make self-consistent, non-LTE calculations …
Detection of Low-Latitude Plumes in the Outer Corona by ULYSSES Radio Ranging Measurements
Woo, Richard
Low-latitude plumes have been detected beyond the field of view of coronagraphs in the range of 23--42 R0 in an equatorial coronal hole by Ulysses radio ranging measurements conducted in 1991 at 13 and 3.6 cm wavelengths. Exploiting the ranging measurement features of high sensitivity, wide dynamic range, high precision, high stability, and long d…
The Interstellar Boron Abundance toward Orion
Meyer, David M.; Jura, M.; Cardelli, Jason A. +1 more
We have used the Goddard High-Resolution Spectrograph to measure the abundance of interstellar boron in several low-density sight lines toward Orion. In particular, we detected the B II 1362 Å line toward λ Ori with an equivalent width (1.0±0.3 mÅ) that implies a B/H abundance ratio (9.1 × 10-11) equal, within the errors, to that found …
Dynamic Processes in Be Star Atmospheres. IV. Common Attributes of Line Profile ``Dimples''
Smith, Myron A.; Thomson, J. R.; Basri, G. S. +3 more
"Dimples" are transient central absorption features flanked by weak emissions commonly seen in the He I λ6678 line profile of the mild B2e star λ Eridani. Smith & Polidan have found that these features can be reproduced with a model in which line photons are scattered within an optically thick (in the line) slab elevated over the surface of a …
ROSAT X-Ray Observations of Four Planetary Nebulae
Kwok, Sun; Leahy, D. A.; Volk, K. +1 more
We report ROSAT Position Sensitive Proportional Counter (PSPC) observations of four planetary nebulae. The observations show that all four nebulae have two-component spectra. A two-component model consisting of a blackbody and a Raymond-Smith thermal plasma is fitted to the observed ROSAT PSPC spectra of NGC t535, Abell 36, and NGC 7293. For all t…
Discovery of a Nova in the Virgo Galaxy M100
Livio, Mario; Madore, Barry F.; Stetson, Peter B. +5 more
We present the V and I light curves of a nova discovered in the disk of the spiral galaxy M100, located in the Virgo Cluster. In spite of the fact that the light curve is not well sampled around maximum light and the reddening to the nova is not accurately known, by adopting the maximum magnitude versus rate of decline relation by Della Valle &…
Hubble Space Telescope Observations of Interstellar Lines in Three High-Latitude Stars
Jenkins, Edward B.; Wallerstein, George
To study changes in the gas-phase abundances of elements in the Galactic halo, we have used the Goddard High Resolution Spectrograph instrument on the Hubble Space Telescope to observe interstellar absorption lines of O I, Mg II, Al II, Al III, Si II, S II, Fe II, and Ni II in the spectra of three stars at high Galactic latitudes: HD 22586, HD 497…