SIMBAD references

The results of a near-infrared study of the Herbig-Haro objects HH 43, HH 54, HH 56, HH 99A, HH 106, and HH 120 are presented. The H- and K-band spectra show molecular hydrogen emission that arises from vibrational levels v' ≤3. The inferred population distribution is thermal in all objects, and can be well described by single excitation temperatures ranging from 2000-2700 K. Non-thermal excitation scenarios, such as fluorescence or H₂ formation in excited levels, or excitations in an UV or X-ray heated gas, are not observed. Emission from [FeII] is present towards all objects. Near-infrared images were obtained towards HH 43, HH 54, and HH 120. The morphology of the H₂ and [FeII] emission is similar on large scales but differs in the detail. The H₂ and [FeII] observations are difficult to reconcile with the predictions of C-type shock models. They indicate the presence of multiple, or curved J-shocks, where [FeII] arises in the faster, dissociative sections, and where H₂ arises in the slow, non-dissociative parts of the shocks.