Molecular emission from the shocked bipolar outflow in OH231.8+4.2

Abstract

We present high-resolution observations of several molecular lines in OH231.8+4.2 taken with the IRAM interferometer. All molecules are distributed in a narrow region along the symmetry axis, and flow outwards following a velocity gradient similar to that found in CO. The HCO+ emission is found to be very clumpy and strongly enhanced in the shock-accelerated lobes, indicating that the formation of this molecule is probably dominated by shock induced reactions. SO is present in the axial outflow as well as in an expanding equatorial disk. The SiO maser emission seems to arise from the innermost parts of such a disk. We also report the first detection of NS in circumstellar envelopes.