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Si/O Abundance Ratios in Extragalactic H II Regions from Hubble Space Telescope UV Spectroscopy
Terlevich, E.; Garnett, D. R.; Skillman, E. D. +5 more
We have measured the Si III] intercombination doublet at 1883 A and 1892 A in seven extragalactic H II regions using the Faint Object Spectrograph on the Hubble Space Telescope. These measurements were used to derive the Si/C and Si/O gas phase abundance ratios in the ionized gas. We find that Si/O shows no systematic variation with O/H over the r…
The flux of interstellar dust observed by ULYSSES and Galileo
Hamilton, D. P.; Grün, E.; Linkert, G. +4 more
Interstellar dust detected by the dust sensor onboard Ulysses was first identified after the Jupiter flyby when the spacecraft's trajectory changed dramatically (Grün et al., 1994). Here we report on two years of Ulysses post-Jupiter data covering the range of ecliptic latitudes from 0° to -54° and distances from 5.4 to 3.2 AU. We find that, over …
A CME-driven solar wind disturbance observed at both low and high heliographic latitudes
McComas, D. J.; Forsyth, R. J.; Goldstein, B. E. +4 more
A solar wind disturbance produced by a fast coronal mass ejection, CME, that departed from the Sun on Feburary 20, 1994 was observed in the ecliptic plane at 1 AU by IMP 8 and at high heliographic latitudes at 3.53 AU by Ulysses. In the ecliptic the disturbance included a strong forward shock but no reverse shock, while at high latitudes the distu…
Vibrationally Excited H 2, HCl, and NO + in the Diffuse Clouds toward zeta Ophiuchi
van Dishoeck, Ewine F.; Federman, S. R.; Lambert, David L. +2 more
Absorption lines from vibrationally excited H2 and from HCl were detected in the ultraviolet spectrum of Zeta Oph with the Hubble Space Telescope (HST). Improved upper limits on NO(+) absorption were obtained as well. The data were analyzed with an updated version of a chemical model for diffuse clouds (van Dishoeck & Black 1986) as a guide to…
The band of solar wind variability at low heliographic latitudes near solar activity minimum: Plasma results from the Ulysses rapid latitude scan
McComas, D. J.; Bame, S. J.; Neugebauer, M. +7 more
Near solar activity minimum large variations in the quiescent solar wind flow are confined to a narrow latitude band centered near the heliographic equator. During Ulysses' recent rapid latitude scan this band was ∼43° wide. Flow parameters poleward of the band in the opposite solar hemispheres were nearly the same. Main entry into the band of var…
Reduction of Galileo and Ulysses dust data
Hamilton, D. P.; Grün, E.; Kissel, J. +4 more
The reduction procedures which are applied to raw data from the Galileo and Ulysses Dust Detectors are described in order to obtain physical parameters (mass and velocity) for the recorded dust impacts. Both detectors are impact ionization detectors which measure the charge released from an impact onto a solid target. From the rise times of the si…
The Hubble Space Telescope Sample of Radio-loud Quasars: The LY alpha /H beta Ratio
Ferland, G. J.; Browne, I. W. A.; Netzer, Hagai +5 more
We have used the first Hubble Space Telescope Faint Object Spectrograph spectra of our sample of radio- loud quasars, and quasi-simultaneous ground-based spectrophotometry, to investigate the intensity ratio Lyα/Hβ, whose small observed values are one of the outstanding problems of active galactic nuclei research. The present sample of 20 quasars …
ULYSSES Observations of Latitude Gradients in the Heliospheric Magnetic Field: Radial Component and Variances
Balogh, A.; Tsurutani, B. T.; Smith, E. J. +3 more
The radial component of the magnetic field at Ulysses, over latitudes from -10° to -45° and distances from 5.3 to 3.8 AU, compares very well with corresponding measurements being made by IMP-8 in the ecliptic at 1AU. There is little, if any, evidence of a latitude gradient. Variances in the field, normalized to the square of the field magnitude, s…
The high-temperature big blue bump in the Seyfert galaxy RE J1034+396
Siemiginowska, A.; Mason, K. O.; Pounds, K. A. +1 more
X-ray, UV and optical spectra are presented for a rare, EUV-bright Seyfert galaxy, RE J1034+396 (z=0.042). When combined, these data describe a very-high temperature big blue bump (BBB; kT_eff~100 eV) whose high energy turnover is observed in soft X-rays. The soft X-ray/UV flux ratio is extremely high, L_0.2keV/L_1200A~10, compared to AGN in gener…
HST Far-Ultraviolet Imaging of Jupiter During the Impacts of Comet Shoemaker-Levy 9
Bertaux, Jean-Loup; Ballester, Gilda E.; Crisp, David +17 more
Hubble Space Telescope far-ultraviolet images of Jupiter during the Shoemaker-Levy 9 impacts show the impact regions darkening over the 2 to 3 hours after the impact, becoming darker and more extended than at longer wavelengths, which indicates that ultraviolet-absorbing gases or aerosols are more extended, more absorbing, and at higher altitudes …