Plasma and magnetic field structure of a slow shock: Wind observations in interplanetary space

This paper reports on the observation of an interplanetary slow shock on May 23, 1995 using 3-s plasma and magnetic field data from the Wind spacecraft. Since the time to traverse the shock (similar to 15 s) is much greater than the 3-s temporal resolution of the data, this observation can reveal the plasma and magnetic field structure through the interior of the shock. The 3-s data also provide accurate preshock and postshock conditions immediately outside the shock layer. The flow speeds in the shock frame of reference U-n < a cos Theta on both sides of the shock, U-n1 > C-S1, and U-n2 < C-S2. Here a and C-S are, respectively, the Alfven speed and the slow speed, Theta is the acute angle between the magnetic field vector and the shock normal, and the subscripts 1 and 2 denote the preshock and the postshock conditions. Theta(1) similar to 47 degrees and Theta(2) similar to 39 degrees. The jump conditions B-2/B-1, N-2/N-1, and (T-i + T-e)(2)/(T-i + T-e)(1) of the observational result are in good agreement with the Rankine-Hugoniot solution. The thickness of the shock is of the order of 36 limes of the preshock ion inertial length.