Search Publications
Chemical Composition of M8 Based on IUE and Visual Observations
Dufour, R. J.; Torres-Peimbert, S.; Peimbert, M.
We present optical and IUE observations of the Hourglass Nebula which is embedded in the galactic H II region M8. By comparing the intensities of the [C III] lines λλ1907 + 1909 with that of C II λ4267, a value of t2 = 0.046±0.01 is obtained. The logarithmic abundances by number of the gaseous component for t2 = 0.046 are: H …
Ultraviolet Observations of Selective Wind Eclipses in gamma Velorum and Evidence for Colliding Winds
Willis, A. J.; Stevens, I. R.; St. -Louis, N.
The paper presents an analysis of all IUE high-resolution spectra available in the archives of the WC8 + O9I binary system Gamma Velorum. The IUE data are supplemented by a series of FUV spectra obtained with the Copernicus satellite covering the whole orbital period. The data reveal substantial UV spectral variations confined to resonance and low…
EGRET Limits on High-Energy Gamma-Ray Emission from X-Ray-- and Low-Energy Gamma-Ray--selected Seyfert Galaxies
Michelson, P. F.; Nolan, P. L.; Thompson, D. J. +13 more
A sample of 22 Seyfert galaxies, 11 type 1 and two type 2 galaxies selected according to their X-ray fluxes in the AGN survey catalogs of EXOSAT and Ginga, two additional type 1 galaxies for which detections in low-energy gamma rays have been reported in the past, plus six more type 1 galaxies and one unclassified Seyfert that have been studied by…
The Abundance of Ammonia in Comet P/Halley Derived from Ultraviolet Spectrophotometry of NH by ASTRON and IUE
Feldman, P. D.; Grinin, V. P.; Fournier, K. B. +1 more
From an analysis of the spatial profiles of both the NH and OH UV emissions observed by the ASTRON satellite, the ratio of ammonia-to-water production rates in Comet Halley on April 9, 1986 is derived and found to lie in the range of 0.44-0.94 percent. In order to compare this result with those based on both ground-based and in situ observations m…
Simultaneous GINGA and IUE Observations of the Seyfert Galaxy NGC 3516
Koyama, Katsuji; Halpern, Jules P.; Awaki, Hisamitsu +2 more
Simultaneous X-ray and UV observations of the Seyfert 1 galaxy NGC 3516 were carried out to investigate the connection between the variable X-ray and ultraviolet absorption features. Over a 2 week period, X-ray spectra Were obtained with Ginga, simultaneously with UV spectra from IUE. The X-ray spectrum was complex and could be fitted satisfactori…
LSIV -12 degrees 111: A Candidate Halo Proto--Planetary Nebula
Dufton, P. L.; Keenan, F. P.; Conlon, E. S. +1 more
We report on multiwavelength observations of LSIV -12 deg 111, which may be an emerging halo planetary nebula. This object was previously classified as a young emission-line B-type star, but a model atmosphere abundance analysis of high-resolution optical spectra has revealed it to be an evolved object, probably in the postasymptotic giant branch …
Hubble Space Telescope Images of the Subarcsecond Jet in DG Tauri
Yang, C.; Hartigan, P.; Kepner, J. +1 more
We have applied a new restoration technique to archival [O~I], H$\alpha$, and continuum HST images of DG~Tau. The restored [O~I] and H$\alpha$ images show that DG~Tau has a jet with a projected length of 25~AU and width $\leq$10~AU, and is already collimated at a projected distance of $\sim$~40~AU (0\farcs25) from the star. Such a narrow width and…
In-Flight Performance and Preliminary Results from the Far Ultraviolet Space Telescope (Faust) Flown on ATLAS-1
Bowyer, Stuart; Lampton, Michael; Sasseen, Timothy P. +1 more
In 1992 March the Far Ultraviolet Space Telescope was flown as part of the NASA ATLAS-1 mission. We describe the in-flight instrument performance and provide a preliminary view of some of the results. Twenty-two wide-field far-ultraviolet images were obtained. At this stage of our analysis, we have far-ultraviolet photometry for more than 4800 sou…
Far-Ultraviolet Radiation from Disk Globular Clusters
Minniti, Dante; Rich, R. M.; Liebert, James
IUE spectra obtained in a survey of the metal-rich disk system of globular clusters are presented. Significant FUV fluxes were detected in the 1200-2000-A short-wavelength (SWP) range of the IUE Observatory in several disk globular clusters. These clusters are the most metal-rich known to have an FUV flux. Three clusters show spectral energy distr…
A Spectroscopic and Photometric Study of FK Comae in 1989
Huenemoerder, David P.; Buzasi, Derek L.; Ramsey, Lawrence W. +1 more
Results of an observational campaign, coordinated between visual photometry, optical spectroscopy, and UV spectroscopy, to elucidate the characteristics of FK Comae are presented. The photometry showed complicated but systematic behavior. Photospheric absorption lines were distorted by a Doppler-shifted bump caused by dark starspots resulting in s…