HCO-21 STAR-FORMING REGION( SPECTROPOLARIMETRY AND MILLIMETER CONTINUUM POLARIMETRY OF THE DR)

We report the results of a search for linear polarization in emission lines toward the outflow lobes of DR 21 (HCO+ J = 1-0), Mon R2 (HCO+ J = 1-0), and IRAS 16293-2422 (CS J = 2-1). Theoretical models suggest linear polarization in optically thin emission lines may be present at the level of a few percent in these regions. However, no polarization was detected. An upper limit of 0.4% can be placed on the polarizatio n toward DR 21 and Mon R2, and 1.2% toward IRAS 16293-2422. Using publ ished HCO+ interferometry of DR 21, we argue that the lack of polariza tion is probably due to the presence of clumpy, turbulent gas, which i s unresolved by our beam (70 '' FWHM). Diminished polarization by mult iple scattering cannot be ruled out. We also present new lambda = 1.3 mm and lambda = 2 mm continuum polarimetry of the DR 21 dust core. Pol arizations of P = 1.7% +/- 0.2% and P = 0.77% +/- 0.13%, respectively, were detected. The lambda = 2 mm polarization is lower than the simil ar to 2.0%-2.5% previously reported at millimeter and submillimeter wa velengths. However, with the unpolarized free-free component of the fl ux density from H II regions in the star-forming core removed, the lev el of polarization is consistent with the previous observations. Based on our observations and those previously reported, there is no clear dependence of level of polarization on beam size in the inner similar to 30 '' of the dust core. The lambda = 2 mm polarization position ang le, 2 degrees +/- 5 degrees, is rotated similar to 20 degrees with res pect to the previous measurements. If the rotation is real, it implies the magnetic field on this expanded scale (42 '' FWHM beam) is more p erpendicular to the general elongation of the dust cloud than it is wi thin the inner 20 '' of the dust core.