Parameters of the positive polarization maximum of the Moon: mapping

Abstract

The distributions of the positive polarization degree maximum P_max and, for the first time, of its phase angle α_max were mapped (for wavelengths γ_eff = 461 nm and 669 nm) on the basis of polarimetric CCD observations of the eastern hemisphere of the Moon. The distributions of the spectropolarimetric index for the positive polarization degree maximum CP_max=P_max(669 nm)/P_max(461 nm) and of the “color” of the maximum polarization angle Cα_max=α_max (669 nm)/ α_max (461 nm) were mapped as well. It has been found that (i) the dependences of α_max on the logarithm of albedo and on the logarithm of P_maxare linearly correlated to a large degree; (ii) the parameters α_max and P_maxdepend on wavelength only due to albedo variations; (iii) there are two branches in the “spectropolarimetric index CP_max–albedo” correlation diagram: mare regions show anti-correlation, and highlands, correlation. The maps obtained in this study can be useful both for developing remote sensing methods for the Moon and other atmosphereless bodies and for testing models of positive polarization of the light reflected by regolith-like surfaces.