Abstract
It is widely accepted that diffusive shock acceleration is an important process in the heliosphere, in particular in producing the energetic particles associated with interplanetary shocks driven by coronal mass ejections. In its simplest formulation shock acceleration is expected to accelerate ions with higher mass to charge ratios less efficiently than those with lower mass to charge. Thus it is anticipated that the Fe/O ratio in shock-accelerated ion populations will decrease with increasing energy above some energy. We examine the circumstances of five interplanetary shocks that have been reported to have associated populations in which Fe/O increases with increasing energy. In each event, the situation is complex, with particle contributions from other sources in addition to the shock. Furthermore, we show that the Fe/O ratio in shock-accelerated ions can decrease even when the shock is traveling through an Fe-rich ambient ion population. Thus, although shock acceleration of an Fe-rich suprathermal population has been proposed to explain large Fe-rich solar particle events, we find no support for this proposal in these observations.
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H.V. Cane, I.G. Richardson, J. Geophys. Res. 108(A4), 1156 (2003). doi:10.1029/2002JA009817
H.V. Cane et al., J. Geophys. Res. 107A(10), 1315 (2002). doi:10.1029/2001JA000320
H.V. Cane, T.T. von Rosenvinge, C.M.S. Cohen, R.A. Mewaldt, Geophys. Res. Lett. 30(12), 8017 (2003). doi:10.1029/2002GRL016580
H.V. Cane et al., J. Geophys. Res. 111, A06S90 (2006). doi:10.1029/2005JA011071
M.I. Desai, G.M. Mason, J.R. Dwyer et al., Astrophys. J. 588, 1149 (2003)
M.I. Desai, G.M. Mason, M.E. Wiedenbeck et al., Astrophys. J. 611, 1156 (2004)
M.I. Desai, G.M. Mason, R.E. Gold et al., Astrophys. J. 649, 470 (2006)
M. Popecki et al., in Proc. 27th Int. Cosmic Ray Conf., vol. 8 (2001), p. 3153
D.V. Reames, Space Sci. Rev. 90, 413 (1999)
I.G. Richardson, The Formation of CIRs at Stream–Stream Interfaces and the Resulting Geomagnetic Activity. AGU Geophysical Monograph, vol. 167 (2006), p. 45
A.J. Tylka et al., Astrophys. J. 625, 474 (2005)
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Cane, H.V., Richardson, I.G. & von Rosenvinge, T.T. Fe/O Ratios in Interplanetary Shock Accelerated Particles. Space Sci Rev 130, 301–307 (2007). https://doi.org/10.1007/s11214-007-9201-7
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DOI: https://doi.org/10.1007/s11214-007-9201-7