Polarimetry of Comet P/Halley - Properties of dust

Abstract

Comet P/Halley was observed polarimetrically for seven nights in IHW and other continuum filters, during its pre- and postpreihelion passages. These polarimetric observations have been combined with the observations taken by other investigators to get a complete picture of phase angle and wavelength dependence of polarization of Comet P/Halley. Assuming Mie-type scattering by cometary grains, observed polarization data have been fitted for different complex values of refractive indices of cometary grains. It has been found that a power-law grain size distribution, suggested by Mazets et al. (1987), with grain size spectrum from 0.001 to 20 microns, fits into the observed data, and the refractive indices of the grains are different at different values of the incident wavelength.