Photometric, Polarization, and Spectrographic Observations of O and B Stars.

This paper consists primarily of a catalogue of 0 and B stars for which observations for polarization, magnitude, color, and spectral types are available. The magnitudes and colors are on the U, B, V system, and the spectral types on the two-dimensional MK system. In addition to the direct observations for magnitude, colors, spectral types, and polarization, the interstellar absorption, the distance modulus, and the ratio of interstellar polarization to absorption are also recorded in the catalogue. The maximum polarization, 0.22 mag., has been found in Cygnus, where the absorption is in excess of 10 mag. An inclination for the Orion-Perseus spiral arms is derived from the alignment of the planes of vibration. The longitude of the radius vector perpendicular to the spiral arm is 102 , in contrast to approximately 135 from 21-cm observations but is in fair agreement with the 0 association data. A maximum value for the ratio of polarization absorption, p/A,,, is determined. A value near 0.06 is indicated from the analysis of the data.