Polarization of white-light solar corona and sky polarization effect during total solar eclipse on March 29, 2006

Abstract

Ground-based total solar eclipse observations are still the key method for coronal investigations. The question about its white-light degree of polarization remains unanswered. There are hypotheses claiming that the degree of polarization in certain regions of the corona may be higher than the maximal theoretically predicted value determined by Thomson scattering.We present polarization of the white-light solar corona observations obtained by three different teams during the March 29, 2006 solar total eclipse. We give an interpretation on how the polarization of the sky impacts brightness of the polarized solar corona, depending on the landscape during the totality. Moreover, it is shown that the singular polarization points of the corona are in linear dependence with the height of the Sun above the horizon.

Detection of polarization neutral points in observations of the combined corona and sky during the 21 August 2017 total solar eclipse

“…Here, we report detailed observations of the combination of coronal polarization and the polarization of the surrounding sky. Such neutral points were predicted by [17], and (hints of them) also observed for earlier solar eclipses [18][19][20][21]. Much in the same fashion as the occurrence of polarization neutral points arXiv:2007.12482v1 [astro-ph.SR] 23 Jul 2020 in the cloud-free sky due to the cancellation of the tangential polarization due to single Rayleigh scattering by the vertical multiple-scattering component, we observe polarization neutral points where the tangential coronal polarization due to Thomson scattering is cancelled by the multiply scattered sky polarization.…”

Why total solar eclipses are important to science?

“…Such observations also show the impact of the sky polarization on the brightness of the polarized solar corona, depending on the landscape during the totality and that the singular polarization points of the corona are in linear dependence with the height of the Sun above the horizon. This and more results from our polarized corona experiments are published in [10].…”

Polarization of the Daytime Sky

“…Part of our scientific tasks are also related to observations and analysis of astronomical events, based on the polarized light we receive. One of our main subjects of study is related to determining the degree of polarization of white-light solar corona during total solar eclipses [3]. It consists of several different components according to the formation of their emission -E-, K-, F-and T-corona (E-coronaemission corona, radiation from highly ionized atoms/particles in the corona; K-corona -"continuum" corona, scattering of photons (photospheric light) by electrons in the corona; F-corona -"Fraunhofer" corona, scattering of photospheric light by dust particles; T-corona -"thermal" corona, mainly IR emission from interplanetary dust).…”