THE PROPER MOTIONS OF CONDENSATIONS IN A BOW SHOCK FLOW

For over a decade, comparisons of high resolution line profiles with s imple, 3/2-D bow shock models have been used to derive the general pro perties of Herbig-Haro (HH) objects. In particular, the parameters whi ch have been derived are the bow shock velocity, the direction of moti on of the object, and the motion of the environment into which the obj ect is moving. This paper presents an analysis of how to derive these parameters from observations of proper motions of the condensations of a HH object. Simple expressions are derived for determining the relev ant parameters from measurements of the components of the proper motio n velocities along and perpendicular to the projected outflow axis. Th ese prescriptions are then applied to the observed proper motions of H H 1, BH 32 and HH 34, for which we obtain the respective flow paramete rs.