H_2 Emission in Bow Shocks

The relationship of H_2 emission (X's) to bow shocks in stellar jets expected for various models. The shaded areas show regions of optical line emission that arise in the hot gas behind J-shocks in the bow shock and the Mach disk. Arrows denote the velocity of the H_2 with respect to the ambient medium. The jet flows from right to left between the dotted lines in each example.