ENERGETIC PARTICLE OBSERVATIONS AND PROPAGATION IN THE THREE-DIMENSIONAL HELIOSPHERE DURING THE 2006 DECEMBER EVENTS

Journal Article · Sat Oct 10 00:00:00 EDT 2009 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/704/1/469· OSTI ID:21367429

Malandraki, O E ^[1]; Marsden, R G; Tranquille, C ^[2]; Lario, D ^[3]; Heber, B ^[4]; Mewaldt, R A; Cohen, C M. S. ^[5]; Lanzerotti, L J ^[6]; Forsyth, R J ^[7]; Elliott, H A ^[8]; Vogiatzis, I I ^[9]; Geranios, A ^[10]

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1. Institute for Astronomy and Astrophysics, National Observatory of Athens, Metaxa and Vas. Pavlou str., Palaia Pedeli 15236, Athens (Greece)
2. Research and Scientific Support Department of ESA, ESTEC, P.O. Box 299, 2200 AG Noordwijk (Netherlands)
3. Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD (United States)
4. Christian-Albrechts-Universitaet Kiel, Leibnistrasse 11, Kiel, D-24118 (Germany)
5. Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)
6. Center for Solar-Terrestrial Research, New Jersey Institute for Technology, 323 Martin Luther King Boulevard, 101 Tiernan Hall, Newark, NJ 07102-1982 (United States)
7. The Blackett Laboratory, Imperial College of Science and Technology London, Imperial College London, South Kensington campus, London, SW7 2AZ (United Kingdom)
8. Space Science and Engineering, Southwest Research Institute, San Antonio, TX 78238 (United States)
9. Space Science Laboratory, Democritus University of Thrace, Xanthi (Greece)
10. Nuclear and Physics Department, University of Athens, Panepistimioupoli, Ilissia, 15771 Athens (Greece)

We report observations of solar energetic particles obtained by the HI-SCALE and COSPIN/LET instruments onboard Ulysses during the period of isolated but intense solar activity in 2006 December, in the declining phase of the solar activity cycle. We present measurements of particle intensities and also discuss observations of particle anisotropies and composition in selected energy ranges. Active Region 10930 produced a series of major solar flares with the strongest one (X9.0) recorded on December 5 after it rotated into view on the solar east limb. Located over the South Pole of the Sun, at >72{sup 0}S heliographic latitude and 2.8 AU radial distance, Ulysses provided unique measurements for assessing the nature of particle propagation to high latitudes under near-minimum solar activity conditions, in a relatively undisturbed heliosphere. The observations seem to exclude the possibility that magnetic field lines originating at low latitudes reached Ulysses, suggesting either that the energetic particles observed as large solar energetic particle (SEP) events over the South Pole of the Sun in 2006 December were released when propagating coronal waves reached high-latitude field lines connected to Ulysses, or underwent perpendicular diffusion. We also discuss comparisons with energetic particle data acquired by the STEREO and Advanced Composition Explorer in the ecliptic plane near 1 AU during this period.

• OSTI ID: 21367429
• Journal Information: Astrophysical Journal, Vol. 704, Issue 1; Other Information: DOI: 10.1088/0004-637X/704/1/469; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANISOTROPY
EMISSION
ENERGY RANGE
HELIOSPHERE
MAGNETIC FIELDS
MASS
SOLAR FLARES
SOLAR WIND
SUN
THREE-DIMENSIONAL CALCULATIONS
ATMOSPHERES
MAIN SEQUENCE STARS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR FLARES
STELLAR WINDS