The Structure of the Inner HH 34 Jet from Optical Integral Field Spectroscopy

Abstract

We present high spatial resolution optical integral field spectroscopy of a collimated Herbig-Haro jet viewed nearly edge-on. Maps of the line emission, velocity centroid, and velocity dispersion were generated for the H$α$ and [S II] emission features from the inner collimated jet and exciting source region of the HH 34 outflow. The kinematic structure of the jet shows several maxima and minima in both velocity centroid value and velocity dispersion along the jet axis. Perpendicular to the flow direction the velocity decreases outward from the axis to the limb of the jet, but the velocity dispersion increases. Maps of the electron density structure were derived from the line ratio of [S II] 6731/6716 emission. We have found that the jet exhibits a pronounced ``striped'' pattern in electron density; the high $n_e$ regions are at the leading side of each of the emission knots in the collimated jet, and low $n_e$ regions in the down-flow direction. On average, the measured electron density decreases outward from the inner regions of the jet, but the highest $n_e$ found in the outflow is spatially offset from the nominal position of the exciting star. The results of our high spatial resolution optical integral field spectroscopy show very good agreement with the kinematics and electron density structure predicted by the existing internal working surface models of the HH~34 outflow.