UBVR Polarimetry of the Peculiar R-Coronae Star V854-CENTAURI

Abstract

We present UBVR polarimetry V 854 Cen obtained on four nights during February 1991-March 1992. Two sets of measurements are close to two nearby light maxima and the other two during the declines when the star was around 4 mag below the two light maxima. Both the amount and position angle of polarization obtained during one light maximum differ significantly from that obtained during the other and on all four occasions the position angles are nearly independent of wavelength. The wavelength dependence of polarization during the light minimum is much steeper than that during the light maximum and the corresponding position angles differ by ~ 75 degree. During the decline phases the polarized flux is also attenuated by the same factor as the starlight implying that the cloud which obscures the photosphere causing the light fading obscures the scattering region also. This restricts the extent of the scattering region which contributes to the observed polarization at light maximum and early decline phases close to the photosphere. The polarization observed at light minimum, most likely, arises from scattering by dust particles distributed more extensively about the star.