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Imaging of Two Damped Lyman Alpha Absorbers at Intermediate Redshifts
Dickinson, Mark; Pettini, Max; Steidel, Charles C. +1 more
By observing the fields of the QSOs 3C 286 and PKS 1229-021 in the I and K_s_ bands under good seeing conditions, we have resolved faint galaxy images close to the QSO sight lines. The sizes, magnitudes, and colors of these objects suggest that they are the galaxies producing 21 cm absorption at z_abs_ = 0.6922 and 0.3950 in the spectra of 3C 286 …
The early Spectral Evolution of Nova Cassiopeiae 1993
Shore, Steven N.; Sonneborn, George; Hauschildt, Peter H. +3 more
In this paper we describe the evolution of Nova Cas 1993 over the first two months of its outburst. We present an ultraviolet light curve that covers the period from announcement to just after dust began forming in the ejecta (1994 Feb. 15) and International Ultraviolet Explorer (IUE) spacecraft constraints forced us to halt our observations. We h…
Far-Ultraviolet Photometry of the Globular Cluster Omega CEN
O'Connell, R. W.; Bohlin, R. C.; Stecher, T. P. +9 more
We present far-ultraviolet images of the globular cluster omega Centauri obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 mission. A total of 1957 sources are detected at 1620 A to a limiting ultraviolet (UV) magnitude of 16.4 in the central 24 min diameter region of the field and a limit of 15.6 over the rema…
Ultraviolet Interstellar Absorption Line in the LMC: Searching for Hidden SNRs
Chu, Y. -H.; Wakker, B.; Mac Low, M. -M. +1 more
Strong x-ray emission detected in Large Magellanic Cloud (LMC) superbubbles has been explained as the result of interior supernova remnants (SNRs) hitting the dense superbubble shell. Such SNRs cannot be found using conventional criteria. We thus investigate the possibility of using the interstellar absorption properties in the UV as a diagnostic …
Spectroscopic, Orbital, and Physical Properties of the Binary Feige 24 and Detection of Transient He II Absorption in the System
Thorstensen, J. R.; Vennes, S.
We have obtained new high-dispersion optical spectroscopy at Kitt Peak National Observatory (KPNO) and new International Ultraviolet Explorer (IUE) spectroscopy of the white dwarf+red dwarf binary system Feige 24. The optical range shows a composite DA+dM spectrum, together with H I Balmer and He I emission. The orbital phase dependence of the emi…
A Model for the Spectroscopic Variations of the Peculiar Symbiotic Star MWC 560
Michalitsianos, A. G.; Shore, Steven N.; Aufdenberg, Jason P.
In this note, we show that the ultraviolet and optical spectroscopic variability of this unique symbiotic star can be understood in terms of a time variable collimated stellar wind with a rapid acceleration near the source. Using the radial velocities observed during the ultraviolet bright phase, we find that a variation in the mass loss rate of a…
Optical and Ultraviolet Observations of 3C 279 During Outburst
McCollum, B.; Shrader, C. R.; Smith, A. G. +6 more
An ongoing program of photometric monitoring of selected active galactic nuclei has revealed a significant outburst in the optically violently variable QSO 3C 279. The event occurred during May and June of 1992, and was characterized by a peak amplitude of 2.3 mag in the R band. We obtained nearly simultaneous optical and ultraviolet spectroscopy …
The 1992/93 Eclipse of 31 Cygni
Eaton, Joel A.; Bell, Coretta
Extensive new ultraviolet and optical spectra of an atmospheric eclipse define the physical properties throughout the wind and chromosphere of 31 Cyg. These data require mass loss of approximately 3 x 10-8 solar masses/yr in a wind that may merge smoothly into the chromosphere. Considerations of how energy is injected into the wind, how…
Independent Distance Determinations to Milky Way Cepheids in Open Clusters and Associations. I. The Binary Cepheid DL CAS in NGC 129
Welch, Douglas L.; Matthews, Jaymie M.; Gieren, Wolfgang P. +2 more
As an eight-day Cepheid which is both a component of a spectroscopic binary and a member of the open cluster NGC 129, DL Cas is potentially a very accurate calibrator of the period-luminosity (PL) relation and Cepheid mass. From 160 high-precision (sigma less than 1.5 km/s) radial velocity observations made with the CORAVEL and DAO spectrometers -…
Satellite Emission Features in Two Seyfert Galaxies: New Evidence That Radio- Quiet AGN Possess Subrelativistic Winds
Stocke, John T.; Sachs, Elise R.; Shull, Michael +1 more
HST/FOS spectra are presented for three bright Seyfert galaxies including one (PG 1351+64) which possesses blue-displaced absorption features in C IV, Si IV, N V, and Lyα (but not in Mg Il) similar to those seen at high redshift in the broad-absorption-line (BAL) QSOs. Several features of the absorptions in PG 1351+64, including variability seen i…