Search Publications
The IUE Survey for Damped Lyman- alpha and Lyman-Limit Absorption Systems: Evolution of the Gaseous Content of the Universe
Turnshek, David A.; Lanzetta, Kenneth M.; Wolfe, Arthur M.
We present a spectroscopic survey for moderate-redshift absorption features from damped Lyα and Lyman- limit absorption systems. The survey is based on a set of optimally extracted and co-added International Ultraviolet Explorer spectra of QSOs, BL Lac objects, and Seyfert galaxies. Results of this survey are combined with those of previous survey…
Software for the Analysis of Emission Line Nebulae
Shaw, Richard A.; Dufour, Reginald J.
A set of software tools has been developed for the IRAF/STSDAS environment to derive the physical conditions in a low-density (nebular) gas given appropriate diagnostic emission line ratios; and lien emissivities given appropriate emission line fluxes, the electron temperature (T_e) and density (N_e). The package is based on the five-level program…
Near-coeval formation of the Galactic bulge and halo inferred from globular cluster ages
Gilmozzi, Roberto; Rich, R. Michael; Renzini, Alvio +4 more
THE morphology of our Galaxy is characterized by a disk of stars moving on circular orbits, surrounding a central spheroidal body of stars on high-velocity, randomly oriented orbits. The spheroid is further differentiated into an inner bulge and an outer halo; the bulge stars are rich in elements heavier than helium ('metals'), whereas the halo st…
Optical and Ultraviolet Analyses of ZZ Ceti Stars and Study of the Atmospheric Convective Efficiency in DA White Dwarfs
Fontaine, G.; Bergeron, P.; Wesemael, F. +3 more
New high signal-to-noise optical spectrophotometry is presented for 22 ZZ Ceti stars. The atmospheric parameters (Teff log g) and the mass are derived for each object using new model atmospheres and synthetic spectra calculated within the mixing-length theory, as well as recent published mass-radius relationships. Various parameterizati…
The Gaseous Extent of Galaxies and the Origin of Lyman-Alpha Absorption Systems: A Survey of Galaxies in the Fields of Hubble Space Telescope Spectroscopic Target QSOs
Bowen, David V.; Lanzetta, Kenneth M.; Webb, John K. +1 more
We present initial results of an imaging and spectroscopic survey of faint galaxies in fields of Hubble Space Telescope spectroscopic target QSOs. The primary objectives of the survey are (1) to determine the incidence, extent, and covering factor of extended gaseous envelopes of luminous galaxies and (2) to determine the fraction of Lyα absorptio…
Detection of an oxygen atmosphere on Jupiter's moon Europa
Feldman, P. D.; Strobel, D. F.; Weaver, H. A. +2 more
EUROPA, the second large satellite out from Jupiter, is roughly the size of Earth's Moon, but unlike the Moon, it has water ice on its surface1. There have been suggestions that an oxygen atmosphere should accumulate around such a body, through reactions which break up the water molecules and form molecular hydrogen and oxygen2,3
VIRGO: Experiment for Helioseismology and Solar Irradiance Monitoring
Gough, Douglas; Chevalier, André; Domingo, Vicente +22 more
The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to t…
Ulysses solar wind plasma observations from pole to pole
McComas, D. J.; Goldstein, B. E.; Bame, S. J. +8 more
We present Ulysses solar wind plasma data from the peak southerly latitude of -80.2° on 12 September 1994 through the corresponding northerly latitude on 31 July 1995. Ulysses encountered fast wind throughout this time except for a 43° band centered on the solar equator. Median mass flux was nearly constant with latitude, while speed and density h…
Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. VIII. an Intensive HST, IUE, and Ground-based Study of NGC 5548
Veilleux, S.; Shull, J. M.; Malkan, M. A. +109 more
We present the data and initial results from a combined HST/IUE/groundbased spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength monitoring of this galaxy …
Origin of the Solar Wind From Composition Data
Geiss, J.; Gloeckler, G.; von Steiger, R.
The ESA/NASA spacecraft Ulysses is making, for the first time, direct measurements in the solar wind originating from virtually all places where the corona expands. Since the initial two polar passes of Ulysses occur during relatively quiet solar conditions, we discuss here the three main regimes of quasi-stationary solar wind flow: the high speed…