Fine Structure of Interplanetary Shock Front—Results from BMSW Experiment with High Time Resolution

Abstract

The structure of subcritical interplanetary shocks was studied using high time resolution from the BMSW plasma instrument onboard the Spektr-R satellite and MFI magnetometer measurements from WIND. Ion scales of the ramp and wavelength of precursor waves were obtained and compared with results of the bow shock structure study. The comparison of precursor wavelengths, determined experimentally with those determined from dispersion relation for low-Mach, low-beta shocks has showed similar results. This confirms the assumption that the dispersion of oblique magnetosonic waves is the determining factor in the formation of upstream wave trains. On the base of the case study it was shown that damped downstream oscillations of density, velocity, temperature may be generated by the interaction of the inflowing solar wind ions with the reflected gyrating ions inside the ramp. A sequence of six wave trains of magnetosonic whistlers has been observed upstream the ramp of subcritical oblique IP shock. The amplitude of oscillations inside the trains decreased with increasing distance from the ramp. The possible energy dissipation mechanism within the shock front is discussed.