The velocity field and structure of the HH 7-HH 11 complex

An optical long slit spectra study has been conducted of the HH 7-HH 11 complex of Herbig-Haro objects; the spectra have yielded the position-dependence of line profiles, centroid velocity, velocity dispersions, and intensity ratios. These data pertain both to the HH objects and the diffuse matter forming bridges between HH 7, HH 8, and HH 10. The complex appears to encompass two subsystems, of which one consists of only H 11 and exhibits much higher electron densities than the one containing HHs 7, 8 and 10. Three properties of the complex are surprising: (1) the large physical differences between the subsystems, (2) the homogeneity of the HH 7, 8, 10 subsystem, and (3) the fact that all objects, including HH 11, are low excitation objects. Three different scenarios are discussed which may account for these data. (O.C.)