Cool matter distribution in inner solar corona from 2023 total solar eclipse observation

TL;DR

This study reveals the presence of cool neutral iron atoms in the inner solar corona during the 2023 eclipse, challenging the traditional view of a uniformly hot corona and suggesting a more complex thermodynamic structure.

Contribution

It provides the first global maps of neutral iron atoms in the inner solar corona, showing their distribution and contrast with free electron distributions, based on simultaneous dual-band eclipse observations.

Findings

Neutral iron atoms are present in the inner corona, forming a distinct cool matter distribution.

The cool matter distribution differs significantly from the free electron (K-corona) map.

Intensities of neutral atom-induced coronae are small fractions of the K-corona, indicating localized heating processes.

Abstract

Solar corona has been judged to consist of free electrons and highly ionized ions with extremely high temperature as a widely accepted knowledge. This view is changed by our eclipse observations. Distributions of cool matter represented by neutral iron atoms in hot inner solar corona are presented via derived global maps of solar Fraunhofer(F-) and Emission(E-) coronae, compared with those of continuum(Kontinuierlich, K-) corona formed by free electrons. The maps are obtained from simultaneous observations of dual filtering bands centered respectively at 659.4nm and 660.1nm, performed from twin telescopes during the total solar eclipse on April 20, 2023 at Com town of East Timor, assisted for judgement via spectral images obtained by a portable spectrograph. They show respectively presences of these neutral iron atoms yielding 659.3nm and 659.4nm lines in both the quiet sun and active regions. The distribution of the cool matter in form of line depression forms an inner F-corona, different from that of the cool matter in form of line enhancement. Both the distributions show a crucial difference from that of the free electrons represented by the K-corona map. It is also found that intensities of the F-corona and the E-corona induced by these neutral atoms are only small fractions of the K-corona, and the diffusion can be seen clearly in all these maps. They uncover also that the coronal heating resources do not distribute pervasively but likely form a thermodynamic griddle where minor photospheric neutral atoms can escape from the heating into the corona globally.