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GHRS Observations of Cool, Low-Gravity Stars. II. Flow and Turbulent Velocities in the Outer Atmosphere of gamma Crucis (M3.4 III)
Judge, Philip G.; Robinson, Richard D.; Carpenter, Kenneth G.
The Goddard High Resoulution Spectrograph (GHRS) on the Hubble Space Telescope (HST) has been used to obtain medium (R = 20,000) and high (R = 85,000) resoultion UV spectra of chromosphere emission features for the M3.4 III star gamma Cru. Small Science Aperture (SSA) G270M and Echelle-B spectra of selected regions in the 2300-2850 A range were ob…
Low-frequency waves associated with Langmuir waves in solar wind
Stone, R. G.; Thejappa, G.; Wentzel, Donat G.
The Ulysses spacecraft has detected several events of low-frequency electromagnetic waves in association with Langmuir waves in the solar wind. The high time resolution observations show that the Langmuir waves are very intense and occur as broad peaks superposed by collapsing millisecond spikes. The low-frequency waves are identified as electomag…
The far UV variability of the symbiotic star SY Muscae.
Pereira, C. B.; Vogel, M.; Nussbaumer, H.
SY Muscae is a symbiotic star. Its periodic luminosity variation has been followed since the beginning of this century. No outburst or erratic variation has ever been seen. Its light variation is ascribed to eclipses within a binary system. We present FUV observations taken by IUE from 1981 to 1993. These spectra confirm the binary interpretation.…
Ulysses observations of opposed tilts of solar wind corotating interaction regions in the northern and southern solar hemispheres
McComas, D. J.; Forsyth, R. J.; Phillips, J. L. +3 more
Data obtained during Ulysses' rapid northbound traverse across the heliographic equator provide evidence for predicted, opposed north-south tilts of corotating interaction regions formed from streams originating in the northern and southern solar hemispheres respectively. In both hemispheres, reverse waves that were propagating poleward were obser…
Broad NE VIII lambda 744 Emission from the Quasar PG 1148+549
Hamann, Fred; Shields, Joseph C.; Ferland, Gary J. +1 more
We discuss the probable detection of broad Ne VIII λ774 emission from the zɛ = 0.978 quasar PG 1148+549, and we use spectral synthesis calculations to study the physical conditions in the line-forming gas. The theoretical predictions and the measured line wavelength both support Ne VIII λ774 as the most likely identification.
Our c…Observations of Energetic Particles with EPAC on Ulysses in Polar Latitudes of the Heliosphere
Franz, M.; Keppler, E.; Korth, A. +5 more
Measurements with the Energetic Particle Composition instrument (EPAC) aboard Ulysses show particles from near the ecliptic that were apparently accelerated by shocks associated with a corotating interaction region. The particles were detected together with the shocks and even when shocks no longer arrived at Ulysses up to -65^circ of heliographic…
Cometary breakup calculations based on a gravitationally-bound agglomeration model: the density and size of Shoemaker-Levy 9.
Solem, J. C.
By modeling Comet Shoemaker-Levy 9 (1993e) as an agglomeration of identical spherical components, bound together only by gravitation, I obtain several qualitative and quantitative features of the comet's breakup during its close encounter with Jupiter. By comparing the size, number, and spatial distribution of the calculated cometary fragments wit…
The Ulysses south polar pass: Transient fluxes of energetic ions
Balogh, A.; Forsyth, R. J.; Goldstein, B. E. +5 more
Using Ulysses low energy telescope (LET) measurements of protons and alpha particles with energies of ∼1-5 MeV/n, we present first observations of transient energetic particle events in the high latitude heliosphere. Three transient particle events with gradual onsets and time durations of several days have been identified in the LET data at helio…
Multifrequency monitoring of the Seyfert 1 galaxy NGC 4593 - II. A small, compact nucleus?
Glass, I. S.; Clavel, J.; Peterson, B. M. +4 more
We discuss the results of a campaign to monitor spectral variations in the low-luminosity Seyfert 1 galaxy NGC 4593, at X-ray, ultraviolet, optical and near-IR frequencies. The observations and data analysis have been described in a companion paper. The active nucleus in this galaxy is strongly and rapidly variable in all wavebands, implying that …
The Complex Optical to Soft X-Ray Spectrum of Low-Redshift Radio-quiet Quasars. II. Comparison with Free-Free and Accretion Disk Models
Elvis, Martin; Wilkes, Belinda J.; McDowell, Jonathan C. +3 more
We compare the optical to soft X-ray spectral energy distributions (SEDs) of a sample of bright low-redshift (0.048 < z < 0.155), radio-quiet quasars, with a range of thermal models which have been proposed to explain the optical/UV/soft X-ray quasar emission: (1) optically thin emission from an ionized plasma, (2) optically thick emission f…