STABILITY ANALYSIS OF BOW SHOCKS

We present a linear stability analysis of bow shocks created by the in teraction of a spherical wind moving with respect to its surrounding m edium. The bounding shocks are assumed isothermal and with Mach number M = infinity. Following Soker, we study the evolution of short-wavele ngth perturbations. We find that the motion is unstable in this limit. Moreover, the ratio of the wind velocity upsilon(w) to the star veloc ity upsilon characterizes the stability properties. Bow shocks with f ast winds for which upsilon/upsilon(w) much less than 1 are more stab le than bow shocks with slow winds, i.e., upsilon/upsilon(w) much gre ater than 1.