HELIOSHEATH MAGNETIC FIELDS BETWEEN 104 AND 113 AU IN A REGION OF DECLINING SPEEDS AND A STAGNATION REGION

We examine the relationships between the magnetic field and the radial velocity component VR observed in the heliosheath by instruments on Voyager 1 (V1). No increase in the magnetic field strength B was observed in a region where VR decreased linearly from 70 km s–1 to 0 km s–1 as plasma moved outward past V1. An unusually broad transition from positive to negative polarity was observed during a ≈26 day interval when the heliospheric current sheet (HCS) moved below the latitude of V1 and the speed of V1 was comparable to the radial speed of the heliosheath flow. When V1 moved through a region where VR ≈ 0 (the 'stagnation region'), B increased linearly with time by a factor of two, and the average of B was 0.14 nT. Nothing comparable to this was observed previously. The magnetic polarity was negative throughout the stagnation region for ≈580 days until 2011 DOY 235, indicating that the HCS was below the latitude of V1. The average passage times of the magnetic holes and proton boundary layers were the same during 2009 and 2011, because the plasma moved past V1 during 2009 at the same speed that V1 moved through the stagnation region during 2011. The microscale fluctuations of B in the stagnation region during 2011 are qualitatively the same as those observed in the heliosheath during 2009. These results suggest that the stagnation region is a part of the heliosheath, rather than a 'transition region' associated with the heliopause.