Search Publications
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 …
IUE Temperatures for White Dwarf Stars in and Around the ZZ Ceti Instability Strip
Kepler, S. O.; Nelan, E. P.
We have analyzed all the archival IUE images of the DA4 and DA5 white dwarfs with model atmosphere fluxes incorporating the quasi-molecular opacities to obtain a consistent set of temperatures for both the variables and nonvariables in and around the ZZ Ceti instability strip. We have found four nonvariable stars inside the instability strip. Take…
A detailed X-ray and radio study of the supernova remnant W 44.
Angelini, Lorella; Jones, L. R.; Smith, A.
We analyze EXOSAT and Einstein Observatory X-ray spectra, an Einstein X-ray image, and a detailed VLA radio map of the SNR W44. The diffuse soft X-ray emission, which is only observed from the interior of the SNR, is shown to be largely of thermal origin. The absence of soft X-ray emission from the shell can be explained by the measured line-of-si…
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…
Observations of stellar winds in high-mass X-ray binaries : evidence for a non-monotonic velocity structure.
van Loon, J. Th.; Hammerschlag-Hensberge, G.; Kaper, L.
We report variations with orbital phase in UV resonance lines of HD77581 (B0.5 Iab), the optical counterpart of the high-mass X-ray binary system Vela X-1 (4U0900-40), occurring at low and intermediate negative velocities. We argue that these variations are caused by ionization effects in the stellar wind by the X-ray source, just like the well-kn…
The soft X-ray excesses of high-luminosity AGN.
Saxton, R. D.; Turner, M. J. L.; Ohashi, T. +3 more
LE and ME spectra of 12 quasars from the EXOSAT data base have been analysed in a search for soft excesses. We have been able to quantify the soft excesses more accurately by using spectral indices for the ME taken from the much more sensitive Ginga observations of the same quasars. Eight quasars show a significant soft excess and the remaining fo…
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…
IK Peg : a nearby, short-period, Sirius-like system.
Stickland, D. J.; Kellett, B. J.; Wonnacott, D.
The system IK Peg has been known to be a binary for over 60 years but the secondary has never been identified. The detection of this system in the British Wide Field Camera All-Sky Survey in the EUV has enabled the secondary to be positively identified as a white dwarf. Fits to EUV survey data, the first IUE spectrum, and archival X-ray data indic…
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…
Ulysses plasma electron observations in the Jovian magnetosphere
McComas, D. J.; Forsyth, R. J.; Bame, S. J. +4 more
The electron analyzer of the solar wind plasma experiment aboard the Ulysses spacecraft measured the plasma properties of the Jovian magnetosphere and surrounding regions during the February 1992 encounter with Jupiter. In addition to sampling a new region of the Jovian magnetosphere, the Ulysses electron measurements were unique in that they incl…