Search Publications
Hubble Space Telescope WFPC Images of Emission Nebulosity near XZ Tauri
Ballester, Gilda E.; Krist, John E.; Crisp, David +14 more
XZ Tauri is a M3 V T Tauri star with a pre-main-sequence binary companion detected by infrared speckle interferometry at a projected separation of 0.3" (about 40 AU). Previous ground-based observations of the system have shown bipolar emission nebulosity, including a possible jet knot. Images obtained with the Wide Field and Planetary Camera 2 on …
HST-GHRS observations of candidate β Pictoris-like circumstellar gaseous disks.
Deleuil, M.; Ferlet, R.; Vidal-Madjar, A. +6 more
We present HST-GHRS observations of four stars in search of β Pictoris-like circumstellar gaseous disks. We detected gas around HR 10, HR 2174 and 51 Oph at large distances from the stars; this gas is circumstellar since the absorption lines from very excited levels require densities incompatible with those found in the diffuse interstellar medium…
A New Pulsation Spectrum and Asteroseismology of delta Scuti.
Templeton, Matthew R.; Bradley, Paul A.; Guzik, Joyce A. +3 more
We present the results of a five-year Strömgren y photometric campaign on δ Scuti. Our data set consists of 6515 discrete differential magnitudes, and spans the period of 1983 June to 1988 September. We found the primary pulsation mode at 59.731129±0.000002 µHz, in close agreement with the frequency determination of Fitch (1976, IAU Colloqui…
Galactic Cosmic-Ray Manganese: Ulysses High Energy Telescope Results
DuVernois, M. A.
The Ulysses High Energy Telescope (HET) allows for a study of Galactic cosmic-ray manganese because of the telescope's excellent mass resolution and large collecting area. The manganese isotopes in the cosmic rays provide a means of studying the parameters of the cosmic-ray propagation in the Galaxy. Each of the isotopes probes a separate aspect o…
Non-LTE model atmosphere analysis of the early ultraviolet spectra of Nova OS Andromedae 1986
Sonneborn, G.; Baron, E.; Shore, Steven N. +4 more
We analyse the early, optically thick, ultraviolet spectra of Nova OS And 1986 using a grid of spherically symmetric, non-LTE, line- blanketed, expanding model atmospheres and synthetic spectra with the following set of parameters: 5000<=T_model<=60000K, solar abundan ces, rho ~r^-3, v_max=2000 km s^-1, L=6x10^4Lsolar, and a statistical or m…
A multiwavelength study of LS II+34 26: a hot post-AGB star in the process of becoming a planetary nebula.
Pottasch, S. R.; de Martino, D.; Parthasarathy, M. +4 more
We present the results from a multiwavelength analysis of LS II+34 26, recently identified as a low mass post-AGB star and not a massive population I B-type star, as previously thought. We confirm that the central star is a carbon-poor post-AGB star surrounded by a very low excitation and compact nebula. Spectroscopic monitoring carried out since …
Latitudinal Variation of Aerosol Sizes Inferred from Titan's Shadow
Karkoschka, Erich; Lorenz, Ralph D.
We measured the location, size, and shape of Titan's shadow in five images taken with the Hubble Space Telescope in 1995. We inferred the altitude of Titan's optical limb at wavelengths of 337-954 nm to an accuracy of 15 km. At each wavelength, altitudes are constant north of -5° and also constant but lower south of -50° latitude, with a linear tr…
Velocity Fields in the Solar Corona during Mass Ejections as Observed with UVCS-SOHO
Romoli, M.; Naletto, G.; Modigliani, A. +20 more
This Letter presents the observations of the first two coronal mass ejections (CMEs) obtained with the Ultraviolet Coronagraph Spectrometer of SOHO. Both CMEs were observed at high spectral resolution in the ultraviolet domain. The first event on 1996 June 6-7 was observed in H I Lyα λ1216 and Lyβ λ1026, O VI λλ1032 and 1037, Si XII λλ499 and 521 …
Accurate optical-to-radio registration of Seyfert galaxies with HST images. Absolute astrometry of HST images.
Macchetto, F. D.; Capetti, A.; Lattanzi, M. G.
We propose a method to obtain accurate absolute astrometry of Hubble Space Telescope images. Ground based images are used to link HST images to standard astrometric stars defining the optical frame of reference. The method has been used to register optical images of the Seyfert 2 galaxy NGC 5929 to the corresponding radio maps, allowing the explor…
NOTE: an HST Search for Magnesium in the Lunar Atmosphere
Parker, Joel Wm.; Stern, S. Alan; Mendillo, Michael +5 more
In October 1996 we used the Hubble Space Telescope's Faint Object Spectrograph to make the first-ever mid-ultraviolet spectroscopic search for emissions from the lunar atmosphere. This spectrum revealed no emission lines, despite the fact that strong resonance emission transitions from the Al, Si, and Mg neutrals and from Mg+occur in th…