POLARIMETRY OF THE HIGHLY REDDENED OPEN CLUSTERS HOGG-15 AND LYNGA-14

We present UBVRI polarimetric observations of stars belonging to the h ighly reddened open clusters Hogg 15 and Lynga 14. The wavelength of m aximum polarization is computed and then analyzed in the context of it s relation to the optical properties and characteristic particle size distribution of the grains responsible for the polarization in each ca se. The amount and direction of the linear polarization are also compu ted. Results indicate that the polarization efficiency is relatively l ow in both cases, compared with the values attributed to the interstel lar medium, and probably due to depolarization effects. Only one out o f the 12 observed members in Hogg 15, and none in Lynga 14, presents i ndications of intrinsic polarization in its measures. There exists som e ''intracluster'' dust in association with Hogg 15, with a slightly d ifferent grain size distribution when compared with the Coalsack dust itself. For Lynga 14, we conclude that the polarization detected in th is case possibly comes from dust present in a nearby cloud located alo ng the line of sight to the cluster, with some dust related to the clu ster itself. The magnetic field in the direction to Hogg 15 follows th e general trend of the polarization directions in the region, but this is not true for Lynga 14, where differences seem to exist.