Search Publications
Compact Nuclei in Moderately Redshifted Galaxies
Green, Richard F.; Griffiths, Richard E.; Ratnatunga, Kavan +1 more
The Hubble Space Telescope (HST) Wide Field Planetary Camera 2 is being used to obtain high-resolution images (<=0."15 FWHM) in the V (F606W) and I (F814W) bands for several thousand distant galaxies as part of the Medium Deep Survey (MDS). An important scientific aim of the MDS is to identify possible active galactic nucleus (AGN) candidates f…
Detection of O VI lambda 1033 Emission and Far-Ultraviolet Spectral Variability in the Gravitational Lens PG 1115+080
Michalitsianos, A. G.; Nichols, J.; Oliversen, R. J.
Far-UV spectra acquired with the International Ultraviolet Explorer (IUE) of the gravitational lens PG 1115+080 and processed with the NEWSIPS software show the presence of prominent O VI λ1033 resonance line emission that is superimposed on strong far-UV continuum between 900 and 1100 A (in the z_QSO_ = 1.722 rest frame). A comparison of these sp…
Observation of the Spin-forbidden Cameron Bands of CO in the Ultraviolet Emission Spectrum of the Red Rectangle
Sitko, Michael L.; Glinski, Robert J.; Reese, Marty D. +1 more
The center of the biconical nebula known as the Red Rectangle has been observed by using the ultraviolet spectrographs aboard the Hubble Space Telescope. We report the observation of phosphorescence of the Cameron bands of CO (a 3 Pi --> X 1 Sigma +) between 1850 and 2600 A. These bands are seen for the first time outside of the solar system. T…
Two-dimensional Ultraviolet Spectral Typing of O-Type Stars
Gies, Douglas R.; Penny, Laura R.; Bagnuolo, William G., Jr.
We present equivalent-width measurements of ultraviolet photospheric lines that are useful as spectral type criteria; these include 23 lines of He II, C III, N III, N IV, O IV, Si III, Si IV, S V, Fe IV, and Fe V in lUE spectra of 67 O3 to BO stars of all luminosity classes. Seven lines and two line ratios are particularly sensitive to spectral ty…
Hubble Space Telescope Observations of Obscuration Rings in Hercules A: Implications for Energy Transport in Powerful Radio Galaxies
Baum, Stefi A.; O'Dea, Christopher P.; Livio, Mario +4 more
We have used the Hubble Space Telescope to obtain snapshot images of Hercules A, the host galaxy to the powerful radio source 3C 348, through a broadband red filter. We report the discovery of interlocking, kiloparsec-scale rings of obscuration aligned near the radio axis and slightly offset from the galaxy's nucleus. We discuss possible models fo…
A Grid of Model Atmospheres and Synthetic Spectra for the Far-Ultraviolet Analysis of Old Stellar Populations
Ferguson, Henry C.; Brown, Thomas M.; Davidsen, Arthur F.
We present a grid of stellar synthetic spectra suitable for detailed comparison to far-ultraviolet (FUV) observations obtained with the Hopkins Ultraviolet Telescope, IUE, and HST. Our specific application is to study the hot stellar populations in elliptical galaxies, but we anticipate that the models will be useful for other purposes. The 1,497 …
Hubble Space Telescope Imaging of Bright Galactic X-Ray Binaries in Crowded Fields
Anderson, Scott F.; Wachter, Stefanie; Margon, Bruce +1 more
We report high spatial resolution HST imagery and photometry of three well-studied, intense Galactic X-ray binaries, X2129 +470, CAL 87, and GX 17 +2. All three sources exhibit important anomalies that are not readily interpreted by conventional models. Each source also lies in a severely crowded field, and in all cases the anomalies would be remo…
The Discovery of an Erupting Dwarf Nova in NGC 6624
Zurek, David R.; Rich, R. Michael; Shara, Michael M.
The core of the globular cluster NGC 6624 has been imaged with the Hubble Space Telescope at three separate epochs. We report the detection of a dwarf nova in eruption at a distance of 5 core radii from the center of the cluster---one of the densest in the Galaxy. This is only the fourth dwarf nova detected in a globular cluster. Our temporal cove…
The 0.8 Day Orbit of the Precataclysmic Binary EUVE J1016-053
Thorstensen, John R.; Bowyer, Stuart; Vennes, Stephane
The optical counterpart of the new extreme ultraviolet source EUVE J1016-053 (= RE 1016-053) is known to show intermittent sharp Balmer and He I emission and traces of an M dwarf associated with a white dwarf optical spectrum. We present extensive optical spectroscopy showing the emission lines vary in velocity and intensity on a period of 0°.7892…
Experimental Pd II Oscillator Strengths and the Palladium Abundance in the HgMn-Type Star chi LUPI
Wahlgren, Glenn M.; Leckrone, David S.; Johansson, Sveneric G. +5 more
Experimental oscillator strengths for 19 ultraviolet lines of Pd II have been derived from measurements of line intensities in calibrated Fourier transform spectra, combined with picosecond-pulse laser measurements of radiative lifetimes. Five of these t9 lines, in addition to other Pd II lines, are present in Hubble Space Telescope/Goddard High-R…