THE PHYSICAL STRUCTURE OF THE HERBIG-HARO OBJECT HH-29

We have obtained Echelle spectra covering a number of important shock diagnostic emission lines, mapping out the full extent of the Herbig-H aro object HH 29. Through this, the velocity field, the level of excit ation and the electron density have all been determined with a spatial resolution of 1 ''-2 '' and a spectral resolution of 10 km s(-1) -20 km s(-1) respectively. Our observations of shock diagnostic lines allo w us to produce an empirical 3D description (velocity is the third dim ension) of F(H alpha), the level of excitation and the electron densit y. Our results indicate that HH 29 is among the Herbig-Haro objects wi th the highest level of excitation. We derive electron densities of be tween a few thousand cm(-3) and 10(4) cm(-3) in 'clumps' interspersed in an 'inter-clump medium' of density similar to 300 cm(-3). The spati al scale of the clumps is less than or similar to 2 '', and the veloci ty dispersion of individual clumps is on the order of 30km s(-1) -50 k m s(-1), implying that the 'knotty' structure obvious in high spatial resolution images also exist in 3 dimensions. Based on the morphologic al and spectroscopical data, HH 29 appears to consist of a number of H H-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 oth ers. We find that HH 29 is best explained as an aggregate of clumps in teracting with ambient material on the side away from the originating source, and also being shocked by a faster wind on the side towards th e originating source.