AbstractThe large gradual solar-energetic-particle (SEP) events, where abundances are commonly measured, are produced when coronal mass ejections (CMEs) drive shock waves through the corona and the interplanetary medium. The shock accelerates particles from the highly-ionized, ∼1.5 MK, plasma in a manner that depends only weakly upon the Q/A of the ion, except at very high energies. Averaging the ∼ MeV/amu abundances over many events compensates for the acceleration effects to produce abundances that appear to correspond directly to those in the coronal source for all observed elements, including H. The resulting abundances reflect the 4 × enhancement of ions with low values of first ionization potential (FIP) arising from ion-neutral fractionation that occurs as the atoms are transported up from the photosphere. A different pattern of fractionation is found for ions that are shock-accelerated from the high-speed solar wind emerging from coronal holes.


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    Title :

    Coronal element abundances derived from solar energetic particles


    Contributors:

    Published in:

    Advances in Space Research ; 14 , 4 ; 177-180


    Publication date :

    1993-01-01


    Size :

    4 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English




    Coronal Element Abundances Derived from Solar Energetic Particles

    Reames, D. V. / COSPAR | British Library Conference Proceedings | 1994




    Coronal Abundances Determined from Energetic Particles

    Reames, D. V. / Committee on Space Research; Scientific Commission E | British Library Conference Proceedings | 1995