Search Publications
The HST Quasar Absorption Line Key Project. IV. HST Faint Object Spectrograph and Ground-based Observations of the Unusual Low-Redshift Broad Absorption Line Quasi-stellar Object PG 0043+039
Turnshek, David A.; Schneider, Donald P.; Savage, Blair D. +10 more
HST FOS observations have shown that the spectrum of the low-redshift (z_em_ ~ 0.384) QSO PG 0043+039 exhibits weak broad absorption lines (BALs). The BALs were discovered during the course of UV spectrophotometry made for the HST Quasar Absorption Line Key Project. The HST data are analyzed along with ground-based optical and IUE spectrophotometr…
Hubble Space Telescope Observations of the Distant Cluster CL 0016+16: Quantitative Morphology of Confirmed Cluster Members
Koo, David C.; Wirth, Gregory D.; Kron, Richard G.
We present Hubble Space Telescope (HST) images of 24 confirmed members of the distant galaxy cluster Cl 0016+16 at redshift 0.55. The Balmer- strong ("E + A") and emission-line galaxies frequently show unusual visual morphology, implying that galaxian interactions produce "active" galaxies in moderate-redshift clusters. We use an image concentrati…
A Search for the Radio Counterpart to the 1994 March 1 Gamma-Ray Burst
Cline, T.; Frail, D. A.; Kulkarni, S. R. +7 more
We report on the results of a search for the radio counterpart to the bright γ-ray burst of 1994 March 1. Using the Dominion Radio Astrophysical Observatory Synthesis Telescope sensitive, wide-field radio images at 1.4 GHz and 0.4 GHz were made of a region around GRB 940301. A total of 15 separate radio images were obtained at each frequency, samp…
WFPC2 Observations of the Globular Cluster M30
Schneider, Donald P.; Yanny, Brian; Bahcall, John N. +1 more
We describe images of the center of the dense globular cluster M30 (NGC 7099) obtained with the Hubble Space Telescope Wide Field/Planetary Camera 2 (HST WFPC2). Data taken in the F336W, F439W, and F555W filters (approximately U, B, and V) yield a color-magnitude diagram with photometric errors of 1 sigma = 0.05 mag for stars with V less than 17.5…
Evidence for a Disk in the Wind of HD 93521: UV Line Profiles from an Axisymmetric Model
Ignace, R.; Bjorkman, J. E.; Cassinelli, J. P. +1 more
Recently it has been suggested (Massa 1992; Howarth & Reid 1993), from the C IV ultraviolet resonance line profile of HD 93521, that there is a high-speed component in the polar outflow from the star as well as a low-speed component in the equatorial regions. In this paper we present theoretical calculations of the line profiles that would be …
Weak Soft X-Ray Excesses Need Not Result from the High-Frequency Tail of the Optical/Ultraviolet Bump in Active Galactic Nuclei
Czerny, Bozena; Zycki, Piotr T.
The broad-band ROSAT/EXOSAT X-ray spectra of six Seyfert 1 galaxies are fitted by a model consisting of a direct power law and a component due to reflection/reprocessing from a partially ionized, optically thick medium. The reflected spectrum contains emission features from various elements in the soft X-ray range. In all objects but one (Mrk 335)…
Properties of the Highly Ionized Disk and Halo Gas toward Two Distant High-Latitude Stars
Sembach, K. R.; Savage, Blair D.
Goddard High Resolution Spectrograph (GHRS) intermediate -resolution observations of S III, Si III, Al III, Si IV, C IV, and N V absorption along the sight lines to HD 18100 (l = 217.9 deg, b = -62.7, d = 3.1 kpc, z = -2.8 kpc) and HD 100340 (l = 258.9 deg, b = +61.2 deg, d = 5.3 kpc, z = 4.6 kpc) are presented. These small science aperture spectr…
Interstellar Detection of the Intersystem Line SI ii] lambda 2335 toward zeta Ophiuchi
Savage, Blair D.; Sofia, Ulysses J.; Cardelli, Jason A. +2 more
We report on the detection of the weak intersystem transistion of Si II lambda 2335 A in the sight line toward zeta Oph using the Ech-B mode (3.5 km/s resolution) of the Goddard High Resolution Spectrograph. The high-quality spectrum is characterized by an empirically measured signal-to-noise of 450, in excellent agreement with that expected from …
The Stellar Population in the Core of M15
Paresce, Francesco; de Marchi, Guido
The inner core of the globular cluster M15 within approximately 2 sec of the geometrical center has been explored with high-resolution images taken through several broad-band UV filter with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). Approximately 210 stars in this region down to a 5 sigma detection limit of m220<…
Variable Extinction in HD 45677 and the Evolution of Dust Grains in Pre--Main-Sequence Disks
Sitko, Michael L.; Halbedel, Elaine M.; Lawrence, Geoffrey F. +2 more
Changes in the UV extinction and IR emission were sought in the Herbig Ae/Be star candidate HD 45677 (= FS CMa) by comparing UV, optical, and IR observations made approximately 10 yr apart. HD 45677 varied significantly, becoming more than 50% brighter in the UV and optical than it was a decade ago. A comparison of the observations between epochs …