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The field horizontal-branch B-type star Feige 86.

Bonifacio, P.; Hack, M.; Castelli, F.

IUE and visible high resolution spectra of the halo B-type star Feige 86 are analyzed with the aim to get further insight into the atmospheric parameters and surface chemical composition of this Pop II star. The analysis is mostly based on the comparison of photometric, spectrophotometric, and spectroscopic observations with color indices, fluxes,…

Numerical Modeling of Coronal Mass Ejections Based on Various Pre-Event Model Atmospheres

Wu, S. T.; Poletto, G.; Suess, S. T. +1 more

We examine how the initial state (pre-event corona) affects the numerical MHD simulation for a coronal mass ejection (CME). Earlier simulations based on a pre-event corona with a homogeneous density and temperature distribution at the lower boundary (i.e., solar surface) have been used to analyze the role of streamer properties in determining the …

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 z_ɛ = 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…