HR: 08:30h
AN: SH51B-02    [Abstracts]
TI: Observations of Suprathermal Power Law Tails with ACE, Ulysses, MESSENGER, and Voyager
AU: * Gloeckler, G
EM: gglo@umich.edu
AF: University of Michigan, Atmospheric, Oceanic and Space Sciences 2455 Hayward St., Ann Arbor, MI 48109-2143, United States
AU: Fisk, L A
EM: lafisk@umich.edu
AF: University of Michigan, Atmospheric, Oceanic and Space Sciences 2455 Hayward St., Ann Arbor, MI 48109-2143, United States
AB: Observations of ubiquitous, suprathermal power law tails with the unique spectral index of –5 on the velocity distributions of solar wind and pickup ions raise important questions and have far reaching consequences. The question of how these tails are formed during quiet times, when no shocks are present, was previously addressed and is briefly reviewed here. One consequence of the existence of these tails during quiet times is that sufficiently energetic particles are always readily available for further acceleration by shocks. To study the evolution of suprathermal tails over a large range of heliocentric distances, we will use proton spectra measured with ACE, Ulysses and Voyager during quiet times as well as upstream and downstream of quasi-stationary and traveling shocks. To look for the first time at suprathermal tails at distances closer to the Sun than 1 AU, we will present our preliminary results from the FIPS instrument on the Mercury MESSENGER Mission. Applying thermodynamic constraints on non-adiabatic heating of upstream particles by a shock, we obtain the downstream –5 power law spectra that are observed and derive an expression for the tail pressure jump across the shock.
DE: 7509 Corona
DE: 7513 Coronal mass ejections (2101)
DE: 7514 Energetic particles (2114)
DE: 7531 Prominence eruptions
DE: 7984 Space radiation environment
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting