Polarization measurements of stars in the region of the nearby molecular cloud MBM 12

Abstract

Linear polarization measurements of stars in the region of the nearby high-latitude molecular cloud MBM 12 are presented. Stars behind the cloud show a polarization of about 2-3 percent, while stars that are in front of the cloud or are projected outside the cloud boundary show very low values (less than 0.5 percent) of polarization. If the polarization is caused by dust grains aligned by a magnetic field, the observed polarization position angles suggest that the field in the cloud is more or less unidirectional and is roughly parallel to the long axis of the cloud. The cloud magnetic field has a direction that is significantly different from that of the local interstellar field, and its strength may be as large as about 60 microG