MULTICOLOR POLARIZATION AND CO OBSERVATIONS TOWARDS A DARK FILAMENT IN MUSCA

Multicolour polarimetry with high sensitivity of stars in the region o f the Musca filamentary cloud and (CO)-C-12 (J = 1 --> 0) observations towards the same area are reported. A lower distance limit of 150 pc is derived for this cloud from a polarization percentage versus distan ce modulus diagram. From the carbon monoxide data, a total mass of 170 solar masses is obtained. The molecular gas density is of the order o f 300 cm-3. The direction of the observed projected interstellar magne tic field is almost perpendicular to the major axis of the cloud. We b elieve that the magnetic field has played a significant role in the ev olution of this cloud. Based on the spatial variation of the ratio of total to selective extinction (R(v) is 3.72 for stars seen close to th e dark filament and 3.37 elsewhere in the region), the grains associat ed with the dark cloud seem to be large in comparison with those usual ly present in the interstellar medium. Based on its distance and radia l velocity, it is suggested that this cloud belongs to Gould's Belt.