The Uranian bow shock: Voyager 2 inbound observations of a high Mach number shock

The Voyager 2 magnetometer and plasma detector measured a high Mach number (fast magnetosonic number MMS> 15), high β (∼ 3) bow shock on the dayside of the Uranian magnetosphere. Although the average conditions on either side of the shock are consistent with the Rankine‐Hugoniot (MHD) relations for a stationary, quasi‐perpendicular shock, the data revealed both detailed structure in the transition region as well as considerable variability in the downstream magnetosheath plasma. The bulk plasma parameters and the magnetic field exhibited some of the characteristics of a supercritical shock: an overshoot followed by damped oscillations downstream, consistent with recent theoretical models of high Mach number quasi‐perpendicular shocks.