A MOLECULAR JET FROM LKH-ALPHA-234

The Herbig Be star LkHalpha 234 possesses both a molecular outflow and an optical jet. New CO J = 3-2 observations with 14'' resolution show that the redshifted CO outflow is collimated, with an axis opposite the blueshifted optical jet. A narrow CO structure or '' CO jet '' is found, which terminates in a CO-bright spot coincident with the Herbig-Haro object HH 105. The CO bright spot/HH object is probably the working surface of an unseen (because of extinction) shock-ionized jet, where the head of the jet encounters the ambient cloud gas. The CO jet may be ambient gas entrained by the postulated fast ionized jet. The quiescent gas in the region is found to contain a ridge or shell of CO emission within which LkHalpha 234 is embedded. The ridge is very sharply bounded to the west by a molecular cavity, suggesting that the formation of LkHalpha 234 was caused by the shell formation event. Triggered star formation is further supported by the detection of a warm CO clump in the ridge which has the narrow lines (FWHM = 2 km s-1), mass (2 M.) and density (10(5) cm-3) typical of prestellar cores. The temperature of this clump (63 K) is much higher than the less-than-or-equal-to 10 K of most cores, so that it may contain an embedded luminous object as a heat source.