2001A&A...376.1073M

Over the last few years, a number of Herbig-Haro (HH) jets have been discovered within the confines of H II regions. These jets apparently are ejected from low mass stars that are similar to the sources of other ``normal'' HH jets, but the flows show some special characteristics which are a result of the photoionization due to the ionizing photons emitted by the star that excites the H II region. In this paper, we present HH jet models including an external, photoionizing radiation field, and study the effects of increasing ionizing photon fluxes F_* on the structure of the head of the jet. We find that the morphology, the emission line fluxes and the line ratios change drastically as a function of increasing F_*. These results give general guidelines for deciding whether an HH jet actually does lie within an H II region, based on the morphology and spectroscopic characteristics of the object.