Catholic University of America, Washington, D. C. 20064

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 (~ 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 Q 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, Q 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. Q ₁ ~ 47° and Q ₂ ~ 39° . The jump conditions B₂/B₁, N₂/N₁, 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 times of the preshock ion inertial length.

Geophys. Res. Lett., Vol. 25, No. 14, 2625-2628, 1998