A relation between dynamics of coronal mass ejections and production of solar energetic particles

Free access article

Issue		A&A Volume 370, Number 3, May II 2001


Page(s)		1064 - 1070
Section		The Sun
DOI		http://dx.doi.org/10.1051/0004-6361:20010241

A&A 370, 1064-1070 (2001)
DOI: 10.1051/0004-6361:20010241

A relation between dynamics of coronal mass ejections and production of solar energetic particles

L. Kocharov¹, J. Torsti¹, O. C. St. Cyr² and T. Huhtanen¹

¹ Space Research Laboratory, Department of Physics, University of Turku, Turku 20014, Finland
² Computational Physics Inc., NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA

(Received 29 December 2000 / Accepted 12 February 2001)

Abstract
During January 1997-June 1998, the Large Angle Spectroscopic Coronagraph (LASCO) aboard the Solar and Heliospheric Observatory spacecraft (SOHO) registered 670 coronal mass ejections (CMEs). We compare two groups of the 300-800 km s^-1 CMEs: (i) (very) gradually accelerating CMEs with acceleration below $10 {\rm m} {\rm s}^{-2}$ , and (ii) impulsively accelerating CMEs with acceleration $a> 20 {\rm m s}^{-2}$ near the Sun, continuing then with the constant speed across the LASCO field of view. An association of those CMEs with solar energetic particle (SEP) events is studied using the data of the energetic particle experiment ERNE also aboard SOHO. There were no SEP events registered in association with the first group CMEs, whereas about 8% of the second group CMEs produced an enhancement in the ~10 MeV proton flux at SOHO. This result along with a number of additional tests supports an idea that production of SEPs by the moderate speed CMEs depends not only on the final speed but also on the magnitude of acceleration that CME experiences during its liftoff. The SEP-producing CMEs are typified by impulsively accelerating CMEs accompanied by soft X-ray flares and coronal shocks.

Key words: acceleration of particles -- Sun: flares -- Sun: corona -- Sun: particle emission

Offprint request: L. Kocharov, leon.kocharov@srl.utu.fi

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