Search Publications
Mass Outflow in the Nearby Proto--Planetary System beta Pictoris
Grady, C. A.; Kondo, Yoji; Bruhweiler, Frederick C.
Previous spectral studies of circumstallar dust around the nearby, candidate proto-planetary system, Beta Pictoris, has detected only infalling gas. The lack of detectable mass outflow has been critical in the interpretation of the origin of the circumstellar gas and in our understanding of the evolutionary status of the Beta Pictoris system. IUE …
Rotational Modulation in IUE Spectra of Cool Dwarf Chromospheres. I. Data Analysis and Period Search Techniques
Hallam, K. L.; Altner, B.; Endal, A. S.
Time-sequenced IUE spectra of a number of a bright F-K dwarfs have been used to investigate rotational modulation in several important chromospheric and transition emission lines. Stellingwerf's phase dispersion minimization (PDM) technique forms the basis of this time-series analysis of these sparsely sampled, irregularly spaced observational seq…
Faint Object Spectrograph Observations of the Low-Luminosity Seyfert Galaxy NGC 1566
Kriss, G. A.; Blair, William P.; Armus, L. +3 more
FOS observations of the Seyfert galaxy NGC 1566 show it to possess the broad lines characteristic of a typical Seyfert 1 galaxy, even in states of very low luminosity. The continuum, however, is steep (f_v_~v^- 1.5^) with no suggestion of the ultraviolet excess seen in higher luminosity AGNs. The broad emission lines have symmetric profiles, but a…
First Results from the Goddard High-Resolution Spectrograph: Element Abundances as a Function of Velocity in the Neutral Gas toward XI Persei
Ebbets, Dennis C.; Sembach, Kenneth R.; Savage, Blair D. +3 more
Observations of ultraviolet interstellar absorption lines toward Xi Persei obtained with the echelle mode of the Goddard High-Resolution Spectrograph (GHRS) aboard the HST at a resolution of 3.5 km/s are presented. The data for O I, C II, Mg II, S II, Fe II, Si II, Mn II, and Zn II are converted into representations of apparent column density per …
Evidence for a Thermally Unstable Shock Wave in the VELA Supernova Remnant
Raymond, John C.; Balick, Bruce; Wallerstein, George
The emission and absorption line signatures of supernova remnant shock waves provide complementary diagnostic capabilities. This paper presents IUE spectra of the nebulosity and new spectra of HD 72088. Models of the emission and absorption lines from shocked gas are used to derive a shock velocity and elemental depletions. There is evidence from …
Short-Term X-Ray Variability of the BL Lacertae Object PKS 2155-304: Power Spectrum and Cross-Correlation Analysis
Maraschi, L.; Tagliaferri, G.; Stella, L. +2 more
We present a detailed power spectrum and cross-correlation analysis of the X-ray light curves of the BL Lac object PKS 2155 - 304, obtained with EXOSAT. The power spectra show a marked red noise-type variability, with the power increasing steeply toward low frequency. The variability is more pronounced in the 1-6 keV band than in the 0.1-2 keV ban…
First Results from the Faint Object Camera: Imaging the Core of R Aquarii
Boksenberg, A.; Barbieri, C.; Weigelt, G. +16 more
The Faint Object Camera on the HST was pointed toward the symbiotic long-period M7e Mira variable R Aquarii, and very high resolution images of the inner core, mainly in the ionized oxygen emission lines in the optical, are reported. Both images show bright arcs, knots, and filaments superposed on a fainter, diffuse nebulosity extending in a gener…
Inefficient Accretion by the DA2 White Dwarf in V471 Tauri
Mullan, D. J.; Sion, E. M.; Shipman, H. L. +1 more
The results are reported of an analysis of eight-high-resolution International Ultraviolet Explorer (IUE) short-wavelength primary spectra of V471 Tauri, an eclipsing-spectroscopic, precataclysmic binary in the Hyades. The coaddition in velocity space of regions surrounding principle high- and low-excitation ion species on a common velocity scale …
High-Resolution IUE Spectra of the Nova-like Variable IX Velorum
Mauche, Christopher W.
The paper addresses two separate but related studies utilizing high-resolution ultraviolet spectra of the nova-like variable IX Velorum, obtained by the IUE satellite. The observations used in the studies are described, and the velocity offsets of the broad Si IV absorption features and the variability of the shapes of the P Cygni profiles of Si I…
Binary Star Observations with the Hubble Space Telescope Fine Guidance Sensors. I. ADS 11300
Benedict, G. F.; Franz, O. G.; Kreidl, T. J. N. +13 more
According to an orbit based on measures mostly near apastron, the binary ADS 11300 = Hu 581 = WDS 18229 + 1458 passed through periastron in 1984 at an angular separation below 0.1 arcsec. On the assumption that one accurate measurement near periastron may serve to define its orbit, ADS 11300 was selected for Early Release Observation (ERO) with th…