HD-187399 - A MASSIVE INTERACTING BINARY-SYSTEM WITH AN ECCENTRIC ORBIT AND INTENSE MASS-TRANSFER - POLARIMETRIC OBSERVATIONS

The results of polarimetric UBVRI observations of the active interacti ng binary system HD 187399 are presented. The detected variable (with orbital phase) linear polarization is shown to arise from the light sc attering in the shell that surrounds the unseen secondary component. B eing apparently more massive. it accretes matter that flows out of the primary component. An analysis of the polarization variability has yi elded estimates for the orbital inclination, i = 46.degrees 4 +/- 2.de grees 1, and the spatial orientation of the system, Omega = 53 degrees +/- 15 degrees. The derived small inclination explains the absence of eclipses in the light curve without invoking the hypothesis of a prob able compact nature of the secondary.