An Update on Ultra-Heavy Elements in Solar Energetic Particles above 10 MeV/Nucleon
- 53 Downloads
Measurements below several MeV/nucleon from Wind/LEMT and ACE/ULEIS show that elements heavier than Zn (Z=30) can be enhanced by factors of ∼100 to 1000, depending on species, in 3He-rich solar energetic particle (SEP) events. Using the Solar Isotope Spectrometer (SIS) on ACE we find that even large SEP (LSEP) shock-accelerated events at energies from ∼10 to >100 MeV/nucleon are often very iron rich and might contain admixtures of flare seed material. Studies of ultra-heavy (UH) SEPs (with Z>30) above 10 MeV/nucleon can be used to test models of acceleration and abundance enhancements in both LSEP and 3He-rich events. We find that the long-term average composition for elements from Z=30 to 40 is similar to standard solar system values, but there is considerable event-to-event variability. Although most of the UH fluence arrives during LSEP events, UH abundances are relatively more enhanced in 3He-rich events, with the (34<Z<40)/O ratio on average more than 50 times higher in 3He-rich events than in LSEP events. At energies >10 MeV/nucleon, the most extreme event in terms of UH composition detected so far took place on 23 July 2004 and had a (34<Z<40)/O enhancement of ∼250–300 times the standard solar value.
KeywordsSun: abundances Sun: particle emission Sun: coronal mass ejections (CMEs) Sun: flares
Unable to display preview. Download preview PDF.
- H.V. Cane, T.T. von Rosenvinge, C.M.S. Cohen, R.A. Mewaldt, Geophys. Res. Lett. 30 (2003). doi: 10.1029/2002GL016580
- R.A. Leske, C.M.S. Cohen, A.C. Cummings, R.A. Mewaldt, E.C. Stone, M.E. Wiedenbeck, T.T. von Rosenvinge, Proc. 29th Internat. Cosmic Ray Conf. (Pune), vol. 1, (2005a) p. 107 Google Scholar
- R.A. Leske, A.C. Cummings, C.M.S. Cohen, R.A. Mewaldt, E.C. Stone, M.E. Wiedenbeck, T.T. von Rosenvinge, Proc. 29th Internat. Cosmic Ray Conf. (Pune), vol. 2, (2005b) p. 113 Google Scholar
- R.A. Mewaldt, C.M.S. Cohen, G.M. Mason, A.C. Cummings, M.I. Desai, R.A. Leske, J. Raines, E.C. Stone, M.E. Wiedenbeck, T.T. von Rosenvinge, T.H. Zurbuchen, Space Sci. Rev., this volume (2007), doi: 10.1007/s11214-077-9187-1
- M.E. Wiedenbeck, G.M. Mason, E.R. Christian, C.M.S. Cohen, A.C. Cummings, J.R. Dwyer, R.E. Gold, S.M. Krimigis, R.A. Leske, J.E. Mazur, R.A. Mewaldt, P.L. Slocum, E.C. Stone, T.T. von Rosenvinge, in AIP Conf. Proc. 679: Solar Wind Ten, ed. by M. Velli, R. Bruno, F. Malara (2003) p. 652 Google Scholar