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The solar energetic particle event of April 14, 1994, as a probe of shock formation and particle acceleration
Bothmer, V.; MacDowall, R. J.; Cane, H. V. +4 more
Gradual solar energetic particle (SEP) events observed at 1 AU are associated with coronal mass ejections (CME) that drive shocks which are presumed to accelerate the ions and electrons to suprathermal energies. However, high-energy (>30 MeV) proton and (>1 MeV) electron events are nearly always associated with both CMEs and flares, suggesti…
Dynamics and Interaction between a Large-Scale Vortex and the Great Red SPOT in Jupiter
Hueso, R.; Rojas, J. F.; Colas, F. +5 more
A unique large-scale vortex, the White Tropical Oval (WTrO), was first observed in the South Tropical Zone of Jupiter, at the latitude of the Great Red Spot (GRS) in 1983. Its origin is probably related to a period of intense formation of eddies in the Southern edge of the South Equatorial Belt at latitude -20°. The WTrO survived many changes in t…
HST imaging of the globular clusters in the Fornax cluster: NGC1379
Forbes, Duncan A.; Brodie, Jean P.; Grillmair, Carl J. +3 more
We present B and I photometry for ~300 globular cluster candidates in NGC1379, an E0 galaxy in the Fornax cluster. Our data are from both Hubble Space Telescope (HST) and ground-based observations. The HST photometry (B only) is essentially complete and free of foreground/background contamination to ~2 mag fainter than the peak of the globular clu…
Emission lines of [NeIV] in the optical and ultraviolet spectra of gaseous nebulae
Feibelman, W. A.; Keenan, F. P.; Espey, B. R. +5 more
Recent R-matrix calculations of electron impact excitation rates in Ne IV are used to calculate emission line ratio-ratio diagrams involving both the ultraviolet (1602, 2422 and 2424 A) and optical (4714, 4716, 4724 and 4726 A) [Ne IV] transitions, for a range of electron temperatures (T_e=10 000-30 000 K) and electron densities (N_e=10^2-10^6.5 c…
The photosphere and chromosphere of the RS Canum Venaticorum star, II Pegasi. II. A multi-wavelength campaign in August/September 1992
Amado, P. J.; Doyle, J. G.; Sarro, L. M. +14 more
We describe multi-wavelength, simultaneous observations of the RS CVn star, II Pegasi, most of which were obtained during the first three weeks of September 1992. These observations were made using optical and infra-red broad-band photometry, ultraviolet and optical spectroscopy and microwave monitoring. We have detected photospheric spots and chr…
A Search for the Optical Counterpart of the Luminous X-Ray Source in NGC 6652
Anderson, Scott F.; Margon, Bruce; Deutsch, Eric W.
We examine images of the field of X1832-330, the luminous (L_X ~ 10^36 ergs s^-1) X-ray burst source near the center of the globular cluster NGC 6652, in order to identify the optical counterpart for further study. U and B ground-based images allow us to set a limit M_B_0 >~ 3.5 for the counterpart at the time of those observations, provided th…
ISO observations of molecular hydrogen in the DR21 bipolar outflow
Smith, Michael D.; Davis, Christopher J.; Eisloffel, Jochen
We demonstrate that a wide range of molecular hydrogen excitation can be observed in protostellar outflows at wavelengths in excess of 5 mum. Cold H_2 in DR21 is detected through the pure rotational transitions in the ground vibrational level (0-0). Hot H_2 is detected in pure rotational transitions within higher vibrational levels (1-1, 1-2, etc.…
Joint Nançay Radioheliograph and LASCO Observations of Coronal Mass Ejections - I. The 1 July 1996 Event
Llebaria, A.; Michels, D. J.; Schwenn, R. +9 more
The development of a coronal mass ejection on 1 July 1996 has been analyzed by comparing the observations of the LASCO/SOHO coronagraph with those of the Nançay radioheliograph. This comparison brings new insight and very useful diagnosis for the study of CME events. It is shown that the initial instability took place in a small volume located abo…
The separation of the stars in the binary nucleus of the planetary nebula Abell 35
Marsh, T. R.; Lynas-Gray, A. E.; Drew, J. E. +2 more
Using the Planetary Camera on board the Hubble Space Telescope, we have measured the projected separation of the binary components in the nucleus of the planetary nebula Abell 35 to be larger than 0.08 arcsec but less than 0.14 arcsec. The system has been imaged in three filters centred at 2950, 3350 and 5785 Angstroms. The white dwarf primary sta…
Ultraviolet and optical flares on GL 866
O'Donoghue, D.; Butler, C. J.; Drake, S. A. +2 more
We present simultaneous ultraviolet and optical observations of five flares on the very late type M dwarf Gl 866 (dM5.5e). A procedure to estimate the physical parameters of the flaring plasma has been developed using a simplified model of the flare and a comparison of observed and computed Balmer decrements. With this procedure we have determined…