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Propagation of energetic particles in the high‐latitude high‐speed solar wind
Author(s) -
Sanderson T. R.,
Marsden R. G.,
Tranquille C.,
Dalla S.,
Forsyth R. J.,
Gosling J. T.,
McKibben R. B.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl017306
Subject(s) - physics , coronal hole , solar wind , polar , solar energetic particles , spacecraft , latitude , current sheet , coronal mass ejection , field line , astrophysics , range (aeronautics) , heliosphere , heliospheric current sheet , isotropy , anisotropy , polar wind , magnetopause , computational physics , geophysics , magnetic field , astronomy , magnetohydrodynamics , aerospace engineering , quantum mechanics , engineering
We present observations of energetic particles in the energy range ∼1 MeV to ∼100 MeV made by the COSPIN instrument on board the Ulysses spacecraft during the recent second northern polar pass. For a short time during this pass the Ulysses spacecraft was at high heliographic latitude, above the current sheet, and immersed in high‐speed solar‐wind flow coming from the northern polar coronal hole. Four large solar energetic particle events were observed. For the first two or three days of each event, the spacecraft was in a homogeneous region devoid of any structures. We discuss the rise to maximum of these events. We examine the onset time and the anisotropy of the energetic particles. We find that during these events the particle angular distributions were almost isotropic, but with a net outward flow along the magnetic field lines. We conclude that particles reached these high latitudes traveling along the magnetic field lines. We do not find any evidence for cross field diffusion at Ulysses.