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Ultraviolet High-Excitation Fe II Fluorescence Lines Excited by O vi, C iv, and H i Resonance Emission As Seen in IUE Spectra
Feibelman, Walter A.; Johansson, Sveneric; Bruhweiler, Frederick C.
Archival high-dispersion spectra from the IUE are used in a search for Bowen emission lines of Fe II excited by the stronger transition of the O VI resonance doublet. The possibility of using these Fe II emission lines as a diagnostic of the strength of the far-ultraviolet emission of O VI at 1032 A is explored. It is found that the Fe II emission…
The Circumstellar Disks of beta Pictoris Analogs
Cheng, Kwang-Ping; Grady, Carol A.; Kondo, Yoji +2 more
A survey using data from the International Ultraviolet Explorer (IUE) of previously known B and A shell stars with IRAS detections has resulted in the identification of three stars, HD 93563, Sigma Her, and 51 Oph, which have spectral signatures of infalling circumstellar plasma similar to Beta Pic. Two of these systems have infrared flux distribu…
The Ultraviolet Spectrum of Scorpius X-1 as Observed by IUE: 1978--1988
Raymond, J. C.; Kallman, T. R.; Vrtilek, S. D.
The IUE observations of Sco X-1 taken prior to September 1988 are summarized. These data are tested for variability associated with orbital motion and for correlations between the various observables. The continuum spectra are fitted to simple models for accretion disk atmospheres which demonstrate that X-ray heating dominates the outer regions of…
Does SV Centauri Harbor an Accretion Disk?
Linnell, Albert P.; Scheick, Xania
Light synthesis simulation of SV Cen UBV photometry by Drechsel et al. (1982) exhibits appreciable residuals. These residuals, together with large Roche model overcontact but also large calculated intercomponent temperature difference, suggests that the light synthesis Roche model is inapplicable. The substantial rate of period change indicates ra…
First Results from the Goddard High-Resolution Spectrograph: Ultraviolet Spectra of a Starburst Knot in NGC 1068
Hutchings, J. B.; Bruhweiler, F.; Boggess, A. +7 more
We present UV spectroscopy of a circumnuclear starburst knot in the Seyfert 2 galaxy NGC 1068. The spectrum shows the presence of several thousand O and B stars which appear to have formed about 3 million years ago. We also discuss the extinction and interstellar medium in the line of sight.
Observations That Link Infrared Cirrus and Ultraviolet Extinction
Tapia, Mauricio; Hecht, James H.; Hackwell, John A.
Results are presented of UV extinction measurements of 17 stars in the open cluster IC 4665 and of four stars in the open cluster NGC 1647, showing that the UV extinctions of the two clusters stars have different properties. Whereas the stars in NGC 1647 cluster are typical of general interstellar space, the stars in IC 4665 have a small 'linear' …
Faint Object Camera Observations of a Globular Cluster Nova Field
Anderson, Scott F.; Jakobsen, Peter; Bohlin, Ralph C. +2 more
The Faint Object Camera onboard Hubble Space Telescope has obtained U and B images of the field of Nova Ophiuchi 1938 in the globular cluster M14 (NGC 6402). The candidate for the quiescent nova suggested by Shara et al. (1986) is clearly resolved into at least six separate images, probably all stellar, in a region of 0.5 arcsec. Although two of t…
Sulfur-bearing Ions in the Ionosphere of Comet Halley
Reme, H.; Korth, A.; Lin, R. P. +3 more
This paper presents the radial density profiles of the ions corresponding to 35, 45, 47, and 47 amu, inside the ionopause of Comet Halley, obtained by the heavy ion analyzer PICCA on board the Giotto spacecraft. A photochemical model of the outflowing atmosphere/ionosphere, which emphasizes the sulfur chemistry in an H2O-dominated atmosphere, is u…
X-Ray Observations of the Bright Seyfert Galaxy IC 4329A
Singh, K. P.; Rao, A. R.; Vahia, M. N.
We have performed a detailed analysis of the broad-band (0.1-25 keV) EXOSAT observations of the high-luminosity, nearby Seyfert type I galaxy IC 4329A. The observations were carried out on two occasions, 1984 July and 1985 July. The X-ray luminosity decreased by ~35% over one year. A significant short-term variability where the intensity decreased…
Hubble Space Telescope Wide-Field/Planetary Camera Images of Saturn
Faber, S. M.; Ewald, S. P.; Hester, J. J. +12 more
Saturn was recorded in blue, green, and 'red' light with the Wide-Field/Planetary Camera aboard the Hubble Space Telescope. Owing to relatively high signal levels over most of the planet's image, a dramatic improvement in the visibility of image detail was achieved by deconvolving the raw images, which had suffered severely from the spherical aber…