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The Gravitational Lens System Q0957+561 in the Ultraviolet
Michalitsianos, A. G.; Dolan, J. F.; Boyd, P. T. +8 more
Photometric and polarimetric observations of both images of the gravitationally lensed quasar Q0957 + 561 (z_em_ = 1.41) were obtained in the UV in 1993 with the High Speed Photometer on board the Hubble Space Telescope. The images exhibited no significant polarization in a bandpass centered on 2770 A (observer's frame); p <= 3.2% (2 σ upper li…
Phase-resolved IUE and Optical Observations of the Polar BY Camelopardalis
Raymond, J. C.; Zucker, D. B.; Mason, P. +4 more
Time-resolved lUE observations of the asynchronous polar BY Cam (H0538 +608) over a period of 11 days show that the N V 1240 Å emission-line velocity varies on the orbital period, with an amplitude of 368±27 km s-1. The N V flux also varies on the orbital period, with maximum flux corresponding to maximum blue-shift. This behavior is se…
The IUE Spectrum of the Planetary Nebula NGC 6751
Feibelman, Walter A.
We present the first high-dispersion lUE short-wavelength (SWP) spectrum of NGC 6751 (029.2 -05.9) from which log Nc = 3.9±0.05 cm-3, terminal wind velocity v∞ = 2450±150 km s-1, and a maximum mass-loss rate of Mṡ(max) 7.9 × 10-8 Msun yr-1 are determined. Emiss…
A Non-LTE Analysis of the zeta Aurigae B-Type Secondary. I. Determination of the Fundamental Stellar Parameters
Bennett, Philip D.; Brown, Alexander; Linsky, Jeffrey L.
We present a non-LTE model atmosphere analysis of the B star secondary of ζ Aurigae (B5 V+K4 Ib) and determine its stellar parameters. A grid of model atmospheres and synthetic spectra were computed for stellar parameters typical of mid-B stars, using the TLUSTY and SYNSPEC codes of Hubeny with the lines and continua of H and He calculated in non-…
Far-Ultraviolet Spectrum of Fairall 9 with the Hopkins Ultraviolet Telescope
Kriss, Gerard A.; Zheng, Wei; Davidsen, Arthur F. +1 more
We observed the Seyfert 1 galaxy Fairall 9 with the Hopkins Ultraviolet Telescope (HUT) for ~3500 s during the Astro-2 mission. The spectrum covers 820--1840 A with a resolution of ~3 A. The intrinsic far-UV continuum is unattenuated to wavelengths as short as 920 A (~880 A in the galaxy's rest frame) and can be fitted with a power law with f nu ~…
Discovery of Faint Ultraviolet Sources in the Globular Cluster NGC 6624 with the Hubble Space Telescope
Cool, Adrienne M.; Sosin, Craig
Using the Faint Object Camera (FOC) on the Hubble Space Telescope (HST), we have identified three faint ultraviolet sources in the innermost ~15 arcseconds of the globular cluster NGC 6624. These sources are in addition to the previously discovered UV counterpart to the X-ray source 4U 1820-30, which is observed in the same field. At 1400 A, the s…
WFPC2 Images of Multiple Nuclei in Nearby Active Galactic Nuclei
Gorjian, Varoujan
High-resolution images have been made with the Hubble Space Telescope of the cores of three active galaxies: Mrk 348, Mrk 516, and Mrk 789. The 500 s images were taken using the WFPC2 camera with the F606W filter. Each galaxy exhibits structure which may be interpreted as multiple nuclei. Mrk 348 appears to have two nuclei, although it is possible…
The First Search for a Gamma-Ray Burst Quiescent Counterpart in the Extreme Ultraviolet with EUVE
Hurley, K.; Kouveliotou, C.; Li, P. +3 more
The opening of the extreme ultraviolet window by the Extreme Ultraviolet Explorer (EUVE) satellite has provided the unique opportunity to perform the first search for a quiescent gamma-ray burst counterpart at these wavelengths. Such emission might be expected if some bursts are related to nearby hot neutron stars or neutron stars with accretion d…
UV Spectrophotometry of the Hottest Stars from the Southern HK Survey
Beers, Timothy C.; Drilling, John S.
Low-resolution UV spectra have been obtained with the long- and short-wavelength lUE cameras for seven of the hottest stars identified in the ongoing HK objective-prism/interference-filter survey begun by Beers, Preston, & Shectman. These stars are a subset of a sample of some 25,000 stars at high galactic latitude whose objective-prism spectr…
Determination of Plasma Temperatures and Luminosities Using Multiple Extreme-Ultraviolet and X-Ray Filters
Brown, Alexander; Wood, Brian E.; Linsky, Jeffrey L.
We carefully examine the techniques used to infer temperatures of stellar coronal plasmas from the count rates of several broadband instruments in the X-ray and extreme-ultraviolet spectral ranges. In particular, we determine to what extent temperatures can be constrained and the corresponding uncertainties in the luminosities and emission measure…