PLASMA IN THE HELIOSHEATH: 3.5 YEARS OF OBSERVATIONS

Voyager 2 (V2) has observed heliosheath (HSH) plasma since 2007 August. We describe how the plasma has evolved across the HSH. We show that the low solar wind dynamic pressure leads to an inward movement of the termination shock (TS) of about 10 AU to a minimum position of 73 AU in 2010. Near the TS large fluctuations are present in the HSH, but these fluctuations decrease as V2 moves further from the TS. The radial speed slowly decreases and the plasma flow slowly turns tailward. The temperature decreases across the HSH. The radial speed in 2011 remains above 100 km s[superscript –1], which implies that V2 is a substantial distance from the heliopause.United States. National Aeronautics and Space Administration (Jet Propulsion Laboratory (U.S.). Contract 959203)United States. National Aeronautics and Space Administration (Grant NNX08AE49G