HR: 16:00h
AN: SH12C-01    [PDF]
TI: Rapid Slow-Down of the Solar Wind Upstream of the Termination Shock from Strong Electron-Impact Ionization of Interstellar Neutrals: A Possible Explanation of the Voyager Observations
AU: * Gloeckler, G
EM: gg10@umail.umd.edu
AF: University of Maryland, Department of Physics, College Park, MD 20742 United States
AU: Fisk, L A
EM: lafisk@umich.edu
AF: University of Michigan, Space Physics Research Lab 2455 Hayward St., Ann Arbor, MI 48109-2143 United States
AB: Slow-down of the solar wind due to mass-loading from interstellar pickup ions upstream of the heliospheric termination shock may explain the recent Voyager 1 low-energy particle and magnetic field observations. This slowing down of the solar wind is expected to be accompanied by comparable increases in magnetic field strength, B, as is required by the "frozen-in" magnetic field condition. We suggest that the solar wind speed decrease during 2002, and consequently the B increase, is likely to have occurred in two steps: first, the speed decreased gradually due to mass loading by pickup H and He from $\sim$430 km/s at 1 AU to $\sim$350 km/s at 70 AU, and then more rapidly to lower values at $\sim$85 AU, due to, e.g., additional production of pickup ions from electron-impact ionization with enhanced fluxes of suprathermal electrons produced in, e.g., the fast-slow wind stream-stream interaction region associated with the heliospheric current sheet. These additional pickup ions would cause the additional decrease in speed to between $\sim$200 and $\sim$300 km/s at 85 AU, consistent with the solar wind speed inferred from Voyager 1 LECP measurements during 2002-2003 upstream of the termination shock. We will discuss the implications of this scenario on the termination shock location and present some ideas on how the suprathermal electrons may be produced.
DE: 2124 Heliopause and solar wind termination
DE: 2144 Interstellar gas
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting