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A Catalog of X-Ray Spectra of BL Lacertae Objects
Bassani, L.; Ciliegi, P.; Caroli, E.
This paper contains a list of X-ray spectra of BL Lac objects mostly collected from the literature. For a small sample of objects EXOSAT/ME spectra have also been analyzed and included in this list. In the catalog 42 objects are considered (26 radio selected and 16 X-ray selected) for a total of 311 X-ray spectra. For each object we report the X-r…
Ulysses observations of noncorotational flows in the outer dayside Jovian magnetosphere
Balogh, A.; Forsyth, R. J.; Cowley, S. W. H. +3 more
Using data from the Anisotropy Telescopes on the Ulysses spacecraft obtained during the February 1992 encounter with Jupiter, we have derived the bulk velocity of ions in the energy range 0.7-1.3 MeV which were detected in Jupiter's outer magnetosphere (at a jovicentric distance of between ∼80 and ∼110 RJ). The derived ion bulk velocity…
High-velocity tails on the velocity distribution of solar wind ions
Geiss, J.; Gloeckler, G.; Wilken, B. +2 more
Recent observations of the solar wind using the SWICS instrument on the Ulysses spacecraft have shown the presence of high-velocity ``tails'' on the velocity distribution of protons. Similar features have also been observed on the velocity distributions of helium and oxygen ions. Of the order of 1% of the solar wind density is involved in these ta…
Detection of [O ii] lambda 2471 from the Io Plasma Torus
Feldman, P. D.; Moos, H. W.; Strobel, D. F. +2 more
We report the first detection of the O II 2471-A forbidden line from the Io plasma torus. Observations of the east and west torus ansae at 5.7 R(J) on 1992 March 15 and May 1, respectively, using the Goddard High Resolution Spectrograph of the HST have resulted in about 5-sigma detections of the line on both occasions, with line brightnesses of 30…
Short Communication: Optical probing of dust in comet Grigg-Skjellerup from the Giotto spacecraft
Bertaux, J. L.; Levasseur-Regourd, A. C.; Renard, J. B. +3 more
The optical probe experiment (OPE) has provided the first in situ high-resolution optical probing of the very inner coma of a short period comet, during the 10 July 1992 encounter of the Giotto spacecraft with Grigg-Skjellerup. Preliminary results of the encounter are presented below. Indications of entering the dust coma occurred around 17,000 km…
The Spectrum of the Central Star of the Planetary Nebula in M22
Harrington, J. P.; Paltoglou, George
New optical observations of the central star of the planetary nebula IRAS 18333-2357 in the globular cluster M22 show lines of H I, He II, C IV, N IV, and N V. The spectrum closely resembles the sdO star KS 292, which has surface abundances enhanced by products of hydrogen shell burning and helium burning, and an effective temperature of 75,000 K.…
Optically thin H Lyman alpha production on outer planets: Low-energy proton acceleration in parallel electric fields and neutral H atom precipitation from ring current
Bhardwaj, A.; Singhal, R. P.
A Monte Carlo model has been constructed to describe the energization and energy degradation of low-energy protons in an H2 atmosphere in the presence of parallel electric field. The energy spectrum of Ly α collision events is employed to determine the volume emission rate (VER) of H Ly α emissions. Numerical experiments have been perfo…
Intergalactic and galactic clouds on the line of sight to SN 1993J in M 81 seen in IUE spectra.
Bomans, D. J.; Fransson, C.; Kirshner, R. P. +4 more
High resolution IUE spectra of SN 1993J in M81 show the existence of several clouds on the line of sight. These include local galactic gas at 0 km s^-1^, gas in M81 at -130 km s^-1^, a cloud in the halo of the Milky Way near -45 km s^-1^, and an intergalactic cloud near +140 km s^-1^. Arguments for each of these locations are given. There is littl…
Mass loading and velocity diffusion models for heavy pickup ions at comet Grigg-Skjellerup
Coates, A. J.; Neubauer, Fritz M.; Johnstone, A. D. +1 more
We compare model predictions of cometary water group ion densities and the solar wind slow down with measurements made by the Giotto Johnstone plasma analyzer implanted ion sensor at the encounter with comet Grigg-Skjellerup (G-S) on July 10, 1992. The observed slope of the ion density profile on approach to the comet is unexpectedly steep. Possib…
Core sub-structure of elliptical galaxies : the core resolution technique applied to NGC 1399.
Stiavelli, M.; Zeilinger, W. W.; Moller, P.
UBRJK' images, obtained with subarcsecond seeing, are presented and used to derive the core light profile of the elliptical galaxy NGC 1399. These data, combined with an HST PC V band exposure, and high- resolution velocity dispersion data obtained by us are used to show that NGC 1399 is likely to possess a central dark mass concentration. Models …