UBVRI PHOTOMETRY AND POLARIMETRY OF THE STARS IN S-252 (NGC-2175) .2.INTERPRETATION

Photoelectric UBVRI photometry and polarimetry and photographic UBVR p hotometry have been used to study the stellar cluster NGC 2175 associa ted with the H II region-molecular cloud complex Sharpless 252. The co lour excess E(B-V) of stars in NGC 2175 ranges from the foreground col our excess of 0.(m)4 up to 1.(m)7. The distance modulus of S 252 obtai ned by fitting ZAMS to the colour-magnitude diagrams of NGC 2175 is 11 .(m)7+/-0.(m)3 (2.2+/-0.3 kpc). The lower part of the colour-magnitude diagrams of the main cluster contains stars still contracting towards ZAMS indicating an age of the order of one million years for the clus ter. The age of a small subcluster to the east of the H II region is a few million years. High stellar polarizations up to 12 % have been ob served. The average wave-length of the maximum polarization in S 252 i s 0.53+/-0.01 mu m and the polarization efficiency is near the empiric al maximum value 3A(upsilon). The polarization field in S 252 is regul ar but cannot be explained by a single magnetic field direction.