1998A&A...330..327F

We have obtained Echelle spectra covering a number of important shock diagnostic emission lines, mapping out the full extent of the Herbig-Haro object HH 29. Through this, the velocity field, the level of excitation and the electron density have all been determined with a spatial resolution of 1"-2" and a spectral resolution of 10km/s-20km/s respectively. Our observations of shock diagnostic lines allow us to produce an empirical 3D description (velocity is the third dimension) of F(Hα), the level of excitation and the electron density. Our results indicate that HH 29 is among the Herbig-Haro objects with the highest level of excitation. We derive electron densities of between a few thousand cm^–3 and 10⁴cm^–3 in `clumps' interspersed in an `inter-clump medium' of density ∼300cm^–3. The spatial scale of the clumps is ≲2", and the velocity dispersion of individual clumps is on the order of 30km/s-50km/s, implying that the `knotty' structure obvious in high spatial resolution images also exist in 3 dimensions. Based on the morphological and spectroscopical data, HH 29 appears to consist of a number of HH-knots where the shock is located on the side of the object oriented towards the originating source in some and on the opposite side in others. We find that HH 29 is best explained as an aggregate of clumps interacting with ambient material on the side away from the originating source, and also being shocked by a faster wind on the side towards the originating source.