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Directivity and Its Energy Dependence in Solar Flare Energetic Emission
Li, Peng
We have studied 72 solar flares simultaneously observed by the Gamma-Ray Spectrometer (GRS, 0.3-1 MeV) and the Hard X-Ray Burst Spectrometer (HXRBS, 30-500 keV) on the Solar Maximum Mission (SMM). Using the spectral analysis results, we studied spectal and size distribution center-to-limb variations for both instruments. The GRS observations show …
Coronal Heating in Flare Stars: Resonant MHD Absorption?
Mullan, D. J.; Johnson, M.
We report on the occurrence of periodicity in X-rays from certain flare stars. Statistically significant periods in the range 70-200 s are present in Einstein data for EQ Vir, Proxima Cen, and AD Leo. Periodicities are also present (although with lower statistical significance) in ROSAT data for AD Leo, and in EXOSAT data for EQ Vir and AD Leo. In…
V 348 Sagittarii: analysis of the absorption spectrum.
Jeffery, C. S.
The highly variable star V 348Sgr has been variously described as a hot RCrB star, an extreme helium star and a cool Wolf-Rayet ([WC11]) central star of a planetary nebula. Despite the Wolf-Rayet nature of its spectrum, sufficient pure absorption lines are visible to allow the LTE analysis of its photosphere presented in this paper. The weak #1IVλ…
X-ray timing and spectral behaviour of the Rapid Burster
Lewin, Walter H. G.; van Paradijs, Jan; Lubin, Lori M. +3 more
We present an X-ray fast-timing and spectral analysis of the type II bursts and the persistent emission (PE) of the Rapid Burster observed with the EXOSAT Medium-Energy Instrument. The hardness-intensity and colour-colour diagrams of the Rapid Burster are somewhat different from those of the majority of other low-mass X-ray binaries, which fall in…
New kinematic distances of NGC 7009 and BD+30°3639 from UV and radio data
Maciel, W. J.
Measurements of the equivalent width of the interstellar Lymanα line from IUE spectra in the direction of the planetary nebulae NGC 7009 and BD+30°3639 are used to infer the H column density in these directions. Hydrogen 21 cm profiles are also used in connection with the ultraviolet data so that the expected rotation velocities and distances can …
Reconnection on Open Field Lines Ahead of Coronal Mass Ejections
McComas, D. J.; Forsyth, R. J.; Phillips, J. L. +3 more
Plasma and magnetic field signatures from 29 November 1990 indicate that the Ulysses spacecraft passed through a series of interplanetary structures that were most likely formed by magnetic reconnection on open field lines ahead of a coronal mass ejection (CME). This reconnection changed the magnetic topology of the upstream region by converting n…
Response of the lo Plasma Torus to Comet Shoemaker-Levy 9
Thomas, N.; Weaver, H. A.; Smith, T. E. +10 more
Spectroscopic and imaging observations of the lo plasma torus were made in June and July 1994 in conjunction with the encounter of periodic comet Shoemaker-Levy 9 with Jupiter. Characteristic emissions from sulfur and oxygen ions showed a decline of about 30 percent in the extreme ultraviolet and an increase of about 40 percent in the far ultravio…
ULYSSES Observations of Solar Wind Plasma Parameters in the Ecliptic From 1.4 to 5.4 AU and Out of the Ecliptic
Balogh, A.; McComas, D. J.; Goldstein, B. E. +4 more
We report observations of radial and latitudinal gradients of Ulysses plasma parameters. The solar wind velocity increased rapidly with latitude from 0° to 35°, then remained approximately constant at higher latitudes. Solar wind density decreased rapidly from 0° to 35° of latitude, and also was approximately constant beyond that latitude. The mas…
Stream interfaces and energetic ions II: Ulysses test of Pioneer results
Gosling, John T.; Intriligator, Devrie S.; Kunow, Horst +2 more
Ulysses measurements of energetic and solar wind particles taken near 5 AU between 20 and 30 degrees south latitude during a well-developed recurring corotating interaction region (CIR) show that the CIR's corotating energetic ion population (CEIP) associated with the trailing reverse shock starts within the CIR at the stream interface. This is co…
Photoionization modelling based on HST images of Magellanic Cloud planetary nebulae - I. SMCN2 and SMCN5
Barlow, M. J.; Blades, J. C.; Liu, X. -W. +2 more
We construct fully self-consistent, detailed photoionization models for two planetary nebulae (PNe) in the Small Magellanic Cloud (SMC), namely SMC N 2 and SMC N 5, to fit optical and UV spectrophotometric observations as well as HST Faint Object Camera (FOC) narrow-band images taken in the light of Hβ. The derived density structure shows that bot…