Spectroscopic Properties of Herbig-Haro Flows

Abstract

While recent studies of Herbig-Haro (HH) objects have focused less on the details of their spectra than on the hydrodynamics of jets and their working surfaces, many open questions concerning these spectra remain. Attempts to quantitatively explain a wide range of lines for many HH objects point to discrepancies between theory and observation. Some lines (specifically [S II](6716+6731)) are much stronger than predicted by simple plane-shock and bow-shock models, while in general high ionization lines (e.g. lines of [O III], [Ne III] and [S III] in the optical and the [C IV] and [N V] in the ultra-violet) are much weaker than expected, pointing to difficulties with current models. On the other hand, examination of these lines has lent new insight into both the quality of our predictions and the nature of HHoutflows. Examination of many Fe lines have demonstrated that our ability to estimate abundances from faint lines is surprisingly good (or surprisingly consistent). Position velocity diagrams have also been constructed (using forbidden emission lines), allowing outflows to be mapped to within 0.”3 arcseconds of the source star.