Models for the Infrared Cavity of HH 46/47

Abstract

We have modeled the limb-brightened cavity seen in the new Spitzer SpaceTelescope IR images of the southwest lobe of HH 46/47 as the bow shockdriven by an outflow from a young, low-mass star. We present models inwhich the outflow is a perfectly collimated, straight jet, models inwhich the jet precesses, and finally a model in which the outflow takesthe form of a latitude-dependent wind. We study cases in which theoutflow moves into a constant-density cloud and into a stratified cloud.We find that the best agreement with the observed cavity is obtained forthe precessing jet in a stratified cloud. However, the straight jet(traveling in a stratified cloud) also gives cavity shapes close to theobserved one. The latitude-dependent wind model that we have computedgives cavity shapes that are substantially wider than the observedcavity. We therefore conclude that the cavity seen in the Spitzerobservations of the southwest lobe of the HH 46/47 outflow do not seemto imply the presence of a latitude-dependent wind, as it can be modeledsuccessfully with a perfectly collimated jet model.