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Astron. Astrophys. 316, 499-505 (1996)

Joint Ulysses and WIND observations of a particle eventin April 1995

A. Buttighoffer1, M. Pick1, A. Raviart2, S. Hoang3, R.P. Lin4, G.M. Simnett5, L.J. Lanzerotti6, and V. Bothmer7

1 DASOP, URA 2080, Observatoire de Meudon, F-92195 Meudon, France
2 CEA-Saclay, DSM, DAPNIA, Service d'Astrophysique, F-91191, France
3 DESPA, URA 246, Observatoire de Meudon, F-92195 Meudon, France
4 Department of Physics and Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA
5 University of Birmingham, Birmingham, UK
6 AT&T Bell Laboratories, Murray Hill, NJ 07974, USA
7 Space Science Department of ESA, ESTEC, 2200 AG Noordwijk, The Netherlands

Received 16 February 1996 / Accepted 24 July 1996

Abstract. In this paper we analyze a solar particle event that was measured at two locations in the heliosphere. Ulysses was at 40o north heliolatitude and 130o west in heliolongitude from Earth while WIND was near Earth at 1 AU in the ecliptic plane. To establish the origin of the particle events, solar coronal activity is investigated. Direct observational evidence of the association between long-duration electron acceleration and a solar radio noise storm is shown. We also establish that the interplanetary type III burst studied here is produced by successive electron injections from distinct coronal locations. Two particle increases are observed during the event. For the first one, the particles are shown to be from coronal origin; for the second one, which is associated with a Forbush decrease, the particles are primarily shock accelerated. The differences in particle intensities observed at WIND and Ulysses are explained by the nature of the particle propagation to the spacecraft locations.

Key words: interplanetary medium - Sun: particle emission - Sun: radio radiation - Sun: corona

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