CS(2--1) Emission from Dense Gas in the Bipolar Outflow of CRL 618

We have imaged the protoplanetary nebula CRL 618 in the CS(2-1) line at 98 GHz using the Owens Valley Radio Observatory millimeter interferometer with a synthesized beam of sun2."5. For the first time, we have resolved the molecular core of CRL 618: the gas at the systemic velocity of the nebula is distributed like a cross, concentrated along two perpendicular linear structures. We have also detected emission out to the ends of the observing bandpass, which is at ±170 km s-1. The high-velocity gas participates in a bipolar outflow, showing marked displacement with respect to the central source, with the redshifted gas generally to the west and the blueshifted gas to the east of the H II region. The spectrum of the CS line reveals a deep absorption feature that we have partially resolved.