Monte Carlo study of highly polarized cool stars.

A theoretical analysis of the polarization of highly polarized cool stars is presented. A Monte Carlo treatment is used along with the Mie theory of scattering by spherical particles. Silicates only in M stars are considered and graphite only in C stars. It is shown that highly polarized cool stars are surrounded by a thick dust disk whose column density lies between 10 to the 7th and the 11th per square centimeter and which is seen along quasi-equatorial directions. The disk may be naturally associated with a bipolar nebula, producing the greatest amounts of polarization. The described mechanism is unable to explain polarization behavior at long wavelengths where thermal emission exists, and at short wavelengths for some variable stars.