UBVR polarimetry of high-galactic latitude carbon stars

we present ubvr polarimetry and photometry obtained over a period of one year of eight high-galactic latitude carbon stars: v hya, cz hya, r for, r lep, y cvn, t dra, rv aqr, and rt cap. the observed polarization is highest in the u band and highly variable with time. similarly, the polarization in the b band is highly variable but the values are always lower than those in the u band. the origin and variability of the linear polarization in these bands may be explained as dispersion of radiation from the central star at the inner regions of the circumstellar envelope, where grains and molecules are created, destroyed, and stirred by shock waves.