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Energetic Particle Observations and Propagation in the Three-Dimensional Heliosphere During the 2006 December Events

Malandraki, O. E. and Marsden, R. G. and Lario, D. and Tranquille, C. and Heber, B. and Mewaldt, R. A. and Cohen, C. M. S. and Lanzerotti, L. J. and Forsyth, R. J. and Elliott, H. A. and Vogiatzis, I. I. and Geranios, A. (2009) Energetic Particle Observations and Propagation in the Three-Dimensional Heliosphere During the 2006 December Events. Astrophysical Journal, 704 (1). pp. 469-476. ISSN 0004-637X. doi:10.1088/0004-637X/704/1/469.

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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°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.

Item Type:Article
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URLURL TypeDescription
Malandraki, O. E.0000-0002-4751-6835
Mewaldt, R. A.0000-0003-2178-9111
Cohen, C. M. S.0000-0002-0978-8127
Additional Information:© 2009. The American Astronomical Society. Received 14 February 2009, accepted for publication 25 August 2009. Published 23 September 2009. We are thankful to our HI-SCALE colleagues for their support and encouragement. Use of the Ulysses Data System is gratefully acknowledged. The CME catalog used to identify the solar origin of the SEP events is generated and maintained by NASA and the Catholic University of America in co-operation with the Naval Research Laboratory. SOHO is a project of international cooperation between ESA and NASA. We thank Manolis Zoulias for help in producing the final figures. The work at Caltech was supported by NASA under sub-contract SA2715-26309 from the University of California, Berkeley under NASA contract NAS5-03131.
Group:Space Radiation Laboratory
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2009-10
Issue or Number:1
Record Number:CaltechAUTHORS:20150325-154722384
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Official Citation:O. E. Malandraki et al. 2009 ApJ 704 469 doi:10.1088/0004-637X/704/1/469
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56092
Deposited By: Deborah Miles
Deposited On:26 Mar 2015 04:16
Last Modified:10 Nov 2021 20:54

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