MILLIMETER-WAVE SPECTROPOLARIMETRY OF EVOLVED STARS - EVIDENCE FOR POLARIZED MOLECULAR LINE EMISSION

We present spectropolarimetry of CS J = 2-1 emission from the evolved stars IRC + 10216 and CRL 2688 and spectropolarimetry of the HCN J=1-0 transition from CRL 2688. We detected a line-averaged linear polariza tion of similar to 1% toward IRC +10216 on three separate occasions. W e found no evidence for velocity dependence of the polarization within the emission line. A deviation from spherical symmetry in the radiati ve transfer of the envelope is implied because polarization was detect ed toward the central star. The polarization position angle of about - 70 degrees is orthogonal to the envelope elongation apparent in previo us observations. Polarizations of 5.1% +/- 1.5% (1 sigma) and less tha n 0.9% (3 sigma), respectively, were derived for CS and HCN from CRL 2 688.