The Spatial Intensity Distribution of the UV Light in HH Objects. Revisited

Simple kinematical bow shock models have successfully explained many of the observed features in Herbig-Haro objects. It is shown that similar models can be applied to the spatial intensity distribution of the UV lines observed by IUE. Archival IUE spectra have been used for the HH 1, HH 2(H+A^'), HH 2(G+B), HH 24A, HH 32A, HH 43(A+B+C), and HH 47A objects, where the brightest UV lines (C IV λ1549, Si III λ1891, C III] λ1909, C II] λ2326, Mg II λ2799) were studied, as well as the UV continuum (modeled by the hydrogen two-photon continuum). The quality of the IUE data is rather limited due to the broad point spread function and the low signal-to-noise, and therefore the models were degraded to make them comparable to the observations. The physical parameters used in the models were obtained from previous optical studies and varied accordingly to match the observations, but within the known uncertainties. The objects were modeled by a single bow shock model (i.e., HH 1, HH 24A, HH 32A, and HH 47A) or the superposition of two (i.e., HH 2(H+A ') and HH 2(G+B) or more (i.e., HH 43(A+B+C)) of them. The idea was to take into account the complexity of the morphology of these objects, and the contribution to the UV light from different condensations within the IUE aperture.