First polarimetric evidence of the existence of the Kordylewski Dust Cloud at the L4 Lagrange point of the Earth–Moon system

Abstract

ABSTRACT In 1961, Kordylewski found two bright patches near the L5 Lagrange point of the Earth–Moon system. This referred to an accumulation of dust particles, later called as Kordylewski dust cloud (KDC). In spite of the photographic observation of the L5 KDC by Kordylewski and its visual (naked-eyed) or photometric confirmation by others, some astronomers assumed that the KDC cannot exist, because the gravitational perturbation of the Sun may disrupt the stabilizing effect of the triangular Lagrange points L4 and L5 of the Earth and Moon. In 2017, the L5 KDC was observed in two consecutive nights by ground-based imaging polarimetry. So far the L5 KDC has been detected 16 times and the L4 KDC only 5 times. Contrary to the visually, photometrically, and polarimetrically documented existence of the L5 KDC, a polarimetric proof does not exist for the L4 KDC. On 2022 July 3, we were able to detect the polarization signals of the L4 KDC, furthermore on 2021 October 31 we detected polarimetrically again the L5 KDC. In this work, we present the first polarimetric evidence of the existence of the L4 KDC, and corroborate polarimetrically the existence of the L5 KDC for the third time.