ATOMIC AND MOLECULAR OUTFLOW IN DR-21

We present observations of the 21 cm H-0 line and of the J = 3-2 transition of HCO+ in DR 21. The H-0 observations reveal a massive (24 M.) jet which is redshifted by up to 90 km s-1, with peak H-0 column density 2 x 10(21) cm-2. This jet is three orders of magnitude more massive than the H-0 wind seen in HH 7-11 by Lizano et al. and is capable of driving the molecular outflow in DR 21 in a momentum conserving interaction. The molecular line observations show that the outflow in DR 21 contains about 170 M . of dense (approximately 10(5)-10(6) cm-3) material. They also reveal a second cloud core to the west of DR 21 which appears to be associated with H-0 emission from shock dissociation of H-2. A model is presented in which the H-0 jet is formed by recombination of an initially ionized outflow from DR 21.