On Formation Of A Shock Wave In Front Of A Coronal Mass Ejection With Velocity Exceeding The Critical One

New study confirms conclusions made in [6]; according to it, there is a disturbed region expended along the CME propagation direction in front of a coronal mass ejection whose velocity u is lower than the critical uC relative to the surrounding coronal plasma. The time difference brightness (plasma density) in the disturbed region smoothly decreases to larger distances in front of CME. A shock wave forms at u higher than uC in the front part of the disturbed region manifested as a discontinuity in radial distributions of the difference brightness.