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Particle acceleration efficiency and MHD characteristics of CIR-related shocks
Mann, G.; Keppler, E.; Classen, H. -T.
During its southbound journey the Ulysses spacecraft crossed a series of corotating interaction regions (CIRs) building up due to the interaction of fast and slow solar wind streams. We analyse the forward and the reverse shocks marking off the 18 CIR encounters between July 1992 and December 1993. Our investigations look for a correlation between…
SVS 16: The most X-ray luminous young stellar object
Stanke, Thomas; Preibisch, Thomas; Neuhaeuser, Ralph
We present new infrared and X-ray data on the optically invisible infrared source SVS 16 in the NGC 1333 star forming region. We show that SVS 16 is a binary with a separation of 1''. The infrared spectrum displays photospheric atomic and CO absorption lines, and thus shows that SVS 16 is a highly obscured (A_V ~ 26 mag) low mass young stellar obj…
Neutral hydrogen absorption observations of the central region of NGC 5929
Mundell, C. G.; Holloway, A. J.; Pedlar, A. +2 more
We present 0.15-arcsec (25-pc) resolution MERLIN observations of neutral hydrogen absorption detected towards the nuclear region of the type 2 Seyfert galaxy NGC 5929. Absorption is detected only towards the north-eastern radio component with a column density of (6.5+/-0.6)x10^21cm^-2. Based on comparison with an HST WFPC2 continuum image, we prop…
ISO Observations of Isolated Herbig AE/BE Stars
Waters, L. B. F. M.; Waelkens, C.; Malfait, K.
We report on SWS and LWS observations of the circumstellar disks of young stars of a few solar masses. The ISO spectra of these objects present a diversity of emission features of carbon-rich and oxygen-rich grains. The similarity of the forsterite spectra observed for Comet Hale-Bopp and the Haebe star HD100546 is particularly striking and provid…
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…