Proton Velocity Distributions in the Inner Heliosheath Derived from Energetic Hydrogen Atoms Measured with Cassini and IBEX
- Conference date: 14–19 March 2010
- Location: Maui, (Hawaii)
Recent definitive observations of Energetic Hydrogen Atoms (EHAs) with IBEX  and Cassini  allow us to deduce the proton velocity distribution in the region of EHA production. We consider four separate components: (a) the heliosheath (HS) solar wind, (b) HS pickup protons, (c) heliosphere pickup protons and (d) the ‐5 power law suprathermal tails that combine to produce the composite IBEX‐LO, IBEX‐HI and Cassini INCA EHA spectrum measured recently in the Voyager‐1 direction (V‐1). We find that (1) the current heliocentric distance of the heliopause (HP) along V‐1, is and AU using the interstellar neutral H density at the termination shock of 0.115, 0.100 and respectively, with the lower limits estimated using lower limits of the measured EHA differential intensities and assuming that ∼30% of the EHAs come from outside the inner heliosheath; (2) the total particle pressure is remaining constant throughout the HS, although contributions from individual components vary with heliocentric distance from the termination shock (TS); (3) in order to explain the lowest energy published IBEX EHA flux, the amplitude of compressional turbulence is predicted to start increasing at AU, reaching and (4) near the HP, the −5 tail pressure rises, while the heliosphere pickup proton pressure falls. The Fisk and Gloeckler  model for ACR acceleration near the heliopause requires (3) and (4).
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