THE UNUSUAL MORPHOLOGY OF THE HIGH-VELOCITY GAS IN L723 - ONE OUTFLOW OR 2

We have mapped the molecular outflow in L723 in the CO J = 2-1 line. The unusual morphology of the flow which has been revealed in earlier CO J = 1-0 maps is very marked in our data. Our maps of the emission integrated over the entire line wings reveals a striking quadrupolar morphology. It has been suggested that this structure could be due to two separate outflow sources which are virtually coincident or to a single, nonsteady source which is processing. However, in our maps made of the more optically thin emission arising from only the higher velocity intervals in the line wings, the quadrupolar structure transforms into two continuous, roughly semicircular arcs, one on each side of the IRAS source 1915+1907. We interpret these arcs to be the limb-brightened walls of evacuated cavities swept clear by a wind from the IRAS source. Consequently, it appears that L723 contains a single, rather conventional bipolar outflow with an axis oriented from northeast to southwest. The limb brightening of the cavity walls is exceptionally marked, which, along with a very wide opening angle of almost 180° for the cavity walls in the vicinity of the source, accounts for the unusual morphology. Modeling of the CO line results indicates that the molecular gas in the cavity walls has been compressed to densities up to 30 times greater than that of the quiescent ambient gas.