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The Optical--Ultraviolet--Gamma-Ray Spectrum of 3C 279
Kazanas, D.; Ferland, G. J.; Browne, I. W. A. +6 more
We have obtained spectroscopy of the violently variable quasar 3C 279, simultaneous with γ-ray observations, in 1992 April. Our combined optical (McDonald Observatory and CTIO) and ultraviolet (HST) observations, made when the source was faint, show a very steep power-law continuum (Fnu_ is proportional to ν^-1.95^), and strong broad em…
The Nuclear Colors and Morphology of Field Galaxies at Moderate Redshift
Illingworth, Garth D.; Forbes, Duncan A.; Koo, David C. +2 more
Until recently, the study of faint field galaxies has been limited by the spatial resolutions available to ground-based imaging. Here we present HST images with 0-1 resolution for a sample of 203 field galaxies with I <= 22 (corresponding to B <= 24.5). The expected median redshift for such a sample is z ~ 0.5. The high resolution of HST all…
The He i lambda 10830 Line in Classical Cepheids. I. Observations
Sasselov, Dimitar D.; Lester, John B.
Using the Fourier Transform Spectrometer at the Canada-France-Hawaii telescope, we obtained high- resolution, high signal-to-noise ratio spectra of seven classical Cepheids at 1.08 µm. We report the first certain detection of the He I λ10830 line in Cepheids. Three of the Cepheids, X Sgr, η Aql, and ζ Gem, were observed with full phase cover…
The Pursuit of Heavy Elements in the HgMn-Type Star chi Lupi: Observations with the GHRS in the COSTAR ERA
Gilliland, Ronald L.; Lindler, Don J.; Wahlgren, Glenn M. +4 more
Observations of the ultra-sharp-lined HgMn star Chi Lupi made with the Goddard High Resolution Spectrograph (GHRS) after the Hubble Space Telescope (HST) First Servicing Mission display the effect of the Corrective Optics Space Telescope Axial Replacement instrument (COSTAR) upon the spectral resolution of several observing modes. The resolution i…
HST Observations of the [O iii] Emission-Line Region in Markarian 78
Boksenberg, A.; Capetti, A.; Sparks, W. B. +1 more
We present the results of HST observations of Mrk 78, a Seyfert 2 galaxy. Observations were taken with the Faint Object Camera using the F550M, F502M (which includes the [O III] λλ4959, 5007 emission lines), and F130M filters. These are medium band filters centered at 5500, 5020, and 1300 A, respectively. The [O III] image shows a biconical shape …
Analysis of the Early Spectra and Light Curve of SN 1987A
Hauschildt, Peter H.; Ensman, Lisa M.
Numerical modeling of supernova spectra, light curves, and hydrodynamics requires physical inputs, numerical techniques, approximations, and assumptions which must be thoroughly understood in order to study the details of supernova explosions. Here, we discuss some of these in the context of the early evolution of supernova 1987A. Gray radiation-h…
Simultaneous Soft and Hard X-Ray Spectroscopy of AM Herculis with EXOSAT: Discovery of Photospheric Absorption Features
Paerels, Frits; van Teeseling, Andre; Heise, John
We present 0.1-10 keV spectroscopic observations of AM Herculis obtained with the Transmission Grating Spectrometers and Medium Energy experiments on EXOSAT, taken when the object was in its 'reversed X-ray mode.' The observation covers over six binary orbits without interruption, enabling us to analyze the phase and intensity dependence of both t…
On the Velocity Dispersion in the Core of the Globular Cluster M15
Meylan, G.; Mayor, M.; Dubath, P.
A projected velocity dispersion sigmap of 0 = 14.0 km/s is derived from an integrated light spectrum obtained at the European Southern Observatory (ESO) at La Silla, Chile, over a central 6 sec x 6 sec area in the core of the globular cluster M15. Extensive numerical simulations of velocity dispersion determinations from integrated ligh…
A Search for Chromospheric Emission in A-Type Stars Using the Goddard High-Resolution Spectrograph
Gilliland, Ronald L.; Simon, Theodore; Landsman, Wayne B.
We have used the Goddard High-Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST) to search for chromospheric emission in the ultraviolet C II 1335 A lines of eight A-type stars. The B-V colors of these stars range from 0.12 to 0.22. We have detected emission in the spectrum of the A7 V star Altair, but in no other star. We present …
Spectral Variations in the Low-Mass X-Ray Binary 4U 0614+09
Singh, K. P.; Apparao, K. M. V.
We report the X-ray spectra of a binary 4U 0614+09 observed with EXOSAT on five different occasions in 1984 and 1986. In four observations in 1984, the source intensity was 'low' compared to its intensity in the 1986 observation. The source was steady on timescales of 10 to 1000 s in each of the 1984 observations but highly variable during the 198…