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The White-Dwarf Companions of 56 Persei and HR 3643
Bergeron, Pierre; Simon, Theodore; Landsman, Wayne
We have obtained low-dispersion IUE spectra of the stars 56 Persei (F4 V) and HR 3643 (F7 II), as part of a survey of late-type stars with a 1565A flux excess in the TD-1 ultraviolet sky survey. The IUE spectrum of each star reveals the presence of a hot white dwarf companion. We fit the Ly-alpha profile and ultraviolet continuum using pure hydrog…
An O VIII Sequence for Planetary Nebula Nuclei
Feibelman, Walter A.
The detection of O VIII emission lines in ultraviolet and optical spectra of high-excitation planetary nebula central stars suggests an "O VIII Sequence" for these object. Emission lines of O VII are also detected. Seven out of ten central stars for these planetaries are known to be nonradial g-mode pulsators. The stars form a narrow strip when pl…
The Diverse Optical/Ultraviolet Spectra of the Globular Cluster X-ray Sources in NGC 7078 and NGC 6712
Anderson, Scott F.; Margon, Bruce; Downes, Ronald A.
Among the about one dozen luminous X-ray bursters in the cores of globular clusters, only three have optical/UV counterparts unambiguously identified. We have observed two of these counterparts spectroscopically with the low resolution optical and UV gratings of the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope (HST), yielding …
Low Mass Stars in an Outer Field in NGC 6397
Casertano, Stefano; Ballester, Gilda E.; Crisp, David +13 more
We have imagined a field 10' from the center of the globular cluster NGC 6397 in the visible and I bands with WFPC-2 on the HST. AT a level which is severely limited by counting statistics in the small area so far studied, this field is richer in dwarfs with I > 21.5 than the 4.6' radius parallel field discussed by Paresce and colleagues. This …
The Iron Abundance of IOTA Herculis
Grigsby, James A.; Mulliss, Christopher L.; Baer, Gretchen M.
We have obtained coadded, high-resolution IUE spectra of Iota Herculis (B3 IV) in both the short-wavelength (SWP) and long-wavelength (LWP) regions. LTE synthetic spectra with a resolution identical to that of IUE were produced with the Kurucz model atmosphere and spectral synthesis codes ATLAS9/SYNTHE. Model parameters were chosen from the litera…
Formation of the Galaxy: Clues from Globular Cluster Ages and Abundances
Fullton, Laura Kellar
In an effort to bring more data to bear on the problem of the age and formation history of the inner regions of the Milky Way, I undertook a photometric and spectroscopic study of a small sample of globular clusters within 5 kpc of the Galactic center: NGC~6723, NGC~6352 and NGC~5927. The ages and chemical compositions of these clusters provide cl…
UV Observations of Three LMC Be-Star/X-ray Binaries
Hauschildt, P. H.; Cowley, A. P.; Schmidtke, P. C. +4 more
This paper describes IUE ultraviolet observations of three Be-star/X-ray binaries in the LMC: CAL 9, CAL E, and RX J0520.5-6932. Because the optical spectra show evidence of an overlying continuum source, ultraviolet spectra were obtained to further investigate its properties, but no UV emission lines are found. The UV spectra have been compared t…
Camera Artifacts in IUE High-Dispersion Spectra
Crenshaw, D. Michael; Bruegman, Ottow W.; Johnson, Rita +1 more
Sky-background images obtianed with the International Ultraviolet Explorer (IUE) have been analyzed to identify camera artifacts in high-dispersion point-source spectra observed through the large aperture. The camera artifacts are artificial emission features that are apparent in all IUE spectra with exposure times longer than about one hour. The …
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…
The Physics of Massive OB Stars in Different Parent Galaxies. I. Ultraviolet and Optical Spectral Morphology in the Magellanic Clouds
Walborn, Nolan R.; Kudritzki, Rolf-Peter; Lennon, Daniel J. +2 more
HST/FOS and ESO 3.6m/CASPEC observations have been made of 18 stars ranging in spectral type from O3 through B0.5 Ia, half of them in each of the Large and Small Magellanic Clouds, in order to investigate massive stellar winds and evolution as a function of metallicity. The spectroscopic data are initially presented and described here in an atlas …