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Observations of Nearby Interstellar Gas and Dust in the Direction toward the Globular Cluster omega Centauri
Bates, B.; Wood, K. D.
High-resolution spectra of Na I D interstellar lines are presented for six stars which lie within 4°.0 of the globular cluster ω Centauri and at distances in the approximate range 100-600 pc. For one star (HD 116226) we discuss also the Ca II K line profile and spectra obtained with lUE. Sky flux images of the ω Cen field show considerable structu…
Observable implications of tearing-mode instability in Jupiter's nightside magnetosphere
Zimbardo, G.
We consider the implications on observations of tearing-mode instability in Jupiter's nightside magnetosphere. Theoretical developments of the tearing instability are briefly discussed. Using a self-consistent axisymmetric magnetic field model based on the Voyager data, it is found that magnetic reconnection driven by the internal magnetospheric e…
Electron density and temperature in the Io plasma torus from Ulysses thermal noise measurements
Moncuquet, Michel; Meyer-Vernet, Nicole; Hoang, Sang +2 more
During the Ulysses flyby of Jupiter, the spacecraft crossed the outer part of the Io plasma torus along a basically North-to-South trajectory at a Jovicentric distance of about 8 RJ. The quasi-thermal noise measured by the Unified Radio and Plasma Wave (URAP) experiment is used to deduce the electron density and temperature along the tr…
An extended correlation between the Balmer and soft X-ray emission from solar and stellar flares.
Butler, C. J.
The integrated soft X-ray (8-12 Å) fluxes for solar flares, given by Thomas & Teske (1971), have been scaled to the equivalent EXOSAT (0.04-2.0 keV) fluxes using spectra obtained from a variety of rocket-based experiments and a model by Mewe for a 1.5 keV plasma. The data show good agreement with the soft X-ray-Hγ correlation established earli…
The interplanetary magnetic field from 1 to 5 AU: Ulysses observations
Balogh, A.; Tsurutani, B. T.; Forsyth, R. J. +3 more
Observations of the Interplanetary Magnetic Field (IMF), carried out from October 1990 to February 1992, during the in-ecliptic phase of the Ulysses mission, are presented in this paper. The observations were made between 1 and 5.4 AU, during a different phase of the solar cycle from previous missions. The large scale reorganisation of the solar c…
Faint Object Camera Far-Ultraviolet Objective Prism Observations of 12 Z > 3 Quasars
Boksenberg, A.; Barbieri, C.; Weigelt, G. +16 more
We present the first results of an exploratory objective prism survey of the far-ultraviolet (λλ1200-1800) spectra of high-redshift quasars obtained with the Faint Object Camera on-board the Hubble Space Telescope. The prime objective of this survey is to identify one or more candidates among the known quasars at Ζem > 3 with suffici…
The spectral variability of the gamma-ray emission from Geminga and VELA and its implications.
Grenier, I. A.; Hermsen, W.; Henriksen, R. N.
The gamma-ray emissions from Geminga and from the Interpeak 1 component of the Vela pulsar were analyzed in order to compare their spectral properties between 50 MeV and 5 GeV and to study their variability between 1975 and 1982 using the COS-B data. The stability of both sources above about 200 and 300 MeV, respectively, retaining an E exp -2.0 +…
Near-Infrared and Ultraviolet Spectrophotometry of the Young Planetary Nebula Hubble 12
Feibelman, Walter A.; Erwin, Peter; Rudy, Richard J. +2 more
The young planetary nebula Hubble 12 is observed using near-IR and UV spectrophotometry. The brightness of the O I lines, which is greater than in any other planetary nebula yet measured, indicates that fluorescent excitation by stellar continuum is the principal mechanism generating these lines. Extinction, electron density, and electron temperat…
Ulysses observations of auroral hiss at high Jovian latitudes
Bame, S. J.; Kellogg, P. J.; MacDowall, R. J. +8 more
During the Ulysses flyby of Jupiter, a whistler-mode emission was periodically detected by the Unified Radio and Plasma wave (URAP) experiment during intervals when the spacecraft extended to high magnetic latitudes. The signal was detected between the local electron plasma frequency and lower hybrid resonance and appears as a funnel-shaped struct…
CCD astrometry and instrumental (Delta)V photometry of wide visual double stars. III. Differential measurements of often observed southern pairs.
Sinachopoulos, D.; van Dessel, E.
We present accurate relative positions and instrumental visual (Bessel V) magnitude differences of southern wide star components. The mean accuracy of the angular separation is 0.02 arcsecs, which corresponds to 1.5 micron on the CCD chip, and of magnitude difference 0.007 mag/exposure. The program pairs are targets of the HIPPARCOS mission and th…