Abstract
The H alpha/forbidden S II angular offsets in two objects are studied to determine whether the recombination regions behind the objects' bowshocks are spatially resolved in the observations. The Herbig-Haro objects, HH 34 and HH 111, demonstrate angular offsets of this type at 0.4-1.4 arcsec, which correspond to physical separations of (2-9) x 10 exp 15 cm. The spatial offsets are examined in 1D numerical shock models in which the spatial offsets between different emission lines are evaluated. Analytic scaling laws are computed which can reproduce the numerical results for comparison with the observations. If the shock velocity is about 35 km/s, the observations agree with model predictions for the estimated preshock density of about 10/cu cm. The paper concludes that the observations of HH-34 and HH-111 do indicate the spatial resolution corresponding to shock-wave recombination regions.
