A possible observation of a cometary bow shock

Abstract

In February, 1982, an unusual enhancement of the IMF was observed by the Pioneer Venus orbiter at 0.72 AU. The three discontinuities within this large disturbance, previously suggested to be due to the possible passage of a comet, are examined in view of the alternative possibility of their representing the first observation to date of a cometary shock. It is noted that number density, temperature, and velocity changes, as well as the magnetic structure of the discontinuities, are consistent with this hypothesis.