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The Ultraviolet-bright Stars of Omega Centauri, M3, and M13
O'Connell, Robert W.; Hill, Robert S.; Bohlin, Ralph C. +7 more
Two new UV-bright stars detected within 2 arcmin of the center of Omega Cen are spectroscopically investigated with the short-wavelength spectrograph of the IUE. The IUE spectra of the UV-bright stars UIT-1 and UIT-2 in the core of Omega Cen superficially resemble those of Population I mid-B stars. The absorption lines of the core UV-bright stars …
Inner Shell of Optically Thin Gas in Active Galactic Nuclei
Zheng, Wei
The Lyα and Balmer line profiles in more than 50 Seyfert 1 galaxies and QSOs are studied. Approximately 60% of the objects show similar profiles, 25% show smaller FWHM of Hβ or Hα. In five objects the Lyα profiles have stronger wings than the Balmer lines. The Lyα/Balmer ratio increases along both wings, suggesting an inner envelope of a very broa…
Coordinated Ginga, IUE, and VLA Observations of Stellar Activity in sigma 2 Coronae Borealis
Walter, F.; Vilhu, O.; Stern, R. A. +5 more
Observations of the active cool star binary system Sigma(2) Corona Borealis with the Large Area Counters on the Ginga X-ray satellite over 2.5 d, or about two orbital periods, are reported. Throughout the observations, Sigma(2) CrB exhibited X-ray variability on time scales ranging from tens of minutes to hours. The X-ray light curve shows evidenc…
Hubble Space Telescope Spectroscopy of OB Stars in M31
Bianchi, L.; Hutchings, J. B.; Lamers, H. J. G. L. M. +2 more
We have obtained UV spectra of two luminous hot stars in M31 with the Hubble Space Telescope. The stars are of late O and WN spectral type and lie on opposite sides of M31. We derive UV extinction curves for M31 which differ from both the Galaxy and the LMC. We find differences between the 15 absorbers in both lines of sight in M31 and in the Gala…
Imaging of Four Planetary Nebulae in the Magellanic Clouds Using the Hubble Space Telescope Faint Object Camera
Boksenberg, A.; Barbieri, C.; Weigelt, G. +18 more
Using the Faint Object Camera on-board the Hubble Space Telescope, we have obtained images of four planetary nebulae (PNe) in the Magellanic Clouds, namely N2 and N5 in the SMC and N66 and N201 in the LMC. Each nebula was imaged through two narrow-band filters isolating [O III] λ5007 and Hβ, for a nominal exposure time of 1000 s in each filter. Si…
The Ionizing Radiation Field of NGC 4388 and Its Relation to the Extranuclear Emission-Line Regions
Colina, Luis
New long-slit spectroscopic observations of NGC 4388 and the extranuclear emission line regions around it are used to investigate the characteristics of the ionizing source and the structure of the extended emission-line regions. The measured luminosity of the [Fe VII) λ6087 emission line detected in the nucleus of NGC 4388 is interpreted as evide…
From Fairall 9 to High-z Objects: Pattern of Change in Ionization Structure
Zheng, Wei; Binette, Luc; Fang, Li-Zhi
A study of 79 IUE spectra of the Seyfert galaxy Fairall 9 shows a considerable change in the continuum shape which can be characterized by several sections. The flux at 3075 A changes in approximate proportion to the optical and X-ray flux, suggesting that they may be a part of the power law. The apparent fourfold change in the continuum slope bet…
Hubble Space Telescope FOS Observations of KPD 0005+5106: A Subluminous WN-WC Descendant with Ongoing Mass Outflow?
Sion, Edward M.; Downes, Ronald A.
The results are reported of spectroscopic observations of the ultrahigh excitation, helium-rich, prewhite-dwarf KPD 0005 + 5106 obtained with the HST Faint Object Spectrograph (FOS) in 1991 May and July with the red (FOS/RD) and blue (FOS/BL) Digicon detectors. The data reveal a rich line spectrum both in absorption and in emission with ultra-high…
The Spectra of IC 418 and IC 5117 from 1.5 to 1.75 Microns
Kwok, Sun; Zhang, C. Y.
Near-infrared spectra of planetary nebulae IC 418 and IC 5117 in the wavelength range 1.5-1.75 microns are reported. More than 10 members of the Brackett line series are detected superposed on a strong continuum. Analysis of the spectra shows that the observed flux ratios of the Brackett lines are in good agreement with the recombination line theo…
The Unusual Ultraviolet Chromospheric Spectrum of the R Coronae Borealis Star, V854 Centauri (NSV 6708), at Minimum Light
Judge, P. G.; Stanford, S. A.; Clayton, Geoffrey C. +2 more
Results are presented of IUE observations of a decline of the recently discovered R CrB star, V854 Cen. These observations are of particular interest because they include spectra taken at 7 mag below maximum light. The 'chromospheric' emission spectra show striking differences from UV spectra of other R CrB stars in decline. Strong emission appear…