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Titolo:
REAPPEARANCE OF RECURRENT LOW-ENERGY PARTICLE EVENTS AT ULYSSES HI-SCALE IN THE NORTHERN HELIOSPHERE/
Autore:
ROELOF EC; SIMNETT GM; DECKER RB; LANZEROTTI LJ; MACLENNAN CG; ARMSTRONG TP; GOLD RE;
Indirizzi:
JOHNS HOPKINS UNIV,APPL PHYS LAB,JOHNS HOPKINS RD LAUREL MD 20723 UNIV KANSAS,DEPT PHYS LAWRENCE KS 66045 AT&T BELL LABS,LUCENT TECHNOL MURRAY HILL NJ 07904 UNIV BIRMINGHAM,SCH PHYS & SPACE RES BIRMINGHAM B15 2TT W MIDLANDS ENGLAND
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
fascicolo: A6, volume: 102, anno: 1997,
pagine: 11251 - 11262
SICI:
2169-9380(1997)102:A6<11251:RORLPE>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOLAR-WIND; PROTONS; VOYAGER-1; ELECTRONS; REGIONS; STREAM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
24
Recensione:
Indirizzi per estratti:
Citazione:
E.C. Roelof et al., "REAPPEARANCE OF RECURRENT LOW-ENERGY PARTICLE EVENTS AT ULYSSES HI-SCALE IN THE NORTHERN HELIOSPHERE/", J GEO R-S P, 102(A6), 1997, pp. 11251-11262

Abstract

In the high-latitude northern hemisphere of the heliosphere, the Heliosphere Instrument for Spectra Composition and Anisotropy at Low Energies (HI-SCALE) energetic particle detectors on Ulysses have measured quasi-recurrent -26-day increases of 40-65 keV electrons during 11 solar rotations from October 1995 through July 1996. They do not appear onall rotations, but when they do, they are associated with increases in 0.5-1.0 MeV protons (preceding the electron increases by several days) and sometimes with decreases in galactic cosmic rays. The northern recurrences form two series shifted half a solar rotation with respectto each other, unlike the very regular and more intense series of 21 recurrences observed by the same instrument throughout the middle-to-high-latitude southern hemisphere from mid-1993 to the beginning of 1995. Correlated energetic particle measurements from IMP 8 at Earth and Voyagers 1 and 2 at 42-62 AU establish that recurrent events during this period were intrinsically stronger in the southern heliosphere thanin the north. The variability of the northern recurrences is attributed, using a generalization of the model of Fisk [1996], to temporal changes during 1966 in the near-Sun polar magnetic field configuration. These changes would affect the connection of Ulysses via magnetic field lines to the corotating interaction regions at lower latitudes >10 AU beyond the spacecraft, where the low-energy particles are accelerated and the galactic cosmic rays are modulated. The observed evolution of the northern polar coronal structure, as revealed in FeXIV (5303 Angstrom) synoptic maps and confirmed by FeXII (195 Angstrom) images fromthe Extreme Ultra-Violet Imaging Telescope on the SOHO spacecraft, isjust that which is required, according to the model, to explain the evolution of the low-energy particle recurrences as observed by Ulysses/HI-SCALE in the northern heliosphere.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/11/20 alle ore 20:38:41