On the nature of the excitation of Herbig-Haro object 2

VLA observations of the NH3 (1, 1) and NH3 (2, 2) lines toward the HH 2 object using the D configuration are presented. Several small clumps located near HH 2 were detected. These clumps are cold, not greater than 20 K, and with narrow line widths, not greater than 1 km/s. The low temperatures and narrow line widths found in the ammonia clumps imply that they cannot be ambient clumps compressed as a whole by a shock wave. It is suggested that these clumps are random ambient high-density clumps in the way of the collimated wind from VLA 1. Alternatively, they could be random ambient clumps with the observed ammonia emission enhanced by the radiation field generated at the bow shock of the jet, as proposed to explain the HCO(+) emission near HH 1 and HH 2.