The Detectability of Neon Fluorescence and Measurement of the Solar Photospheric Neon Abundance

TL;DR

This study uses Monte Carlo simulations to evaluate the feasibility of detecting neon fluorescence in the solar atmosphere as a direct method to measure the solar photospheric neon abundance, which is challenging to determine otherwise.

Contribution

It introduces a novel approach using Ne Kα fluorescence to directly measure the solar photospheric neon abundance, supported by detailed Monte Carlo modeling.

Findings

Ne Kα line is detectable in quiet Sun conditions.

Equivalent width of the line is approximately 6 mÅ.

Photon flux at Earth suggests feasible detection with current instruments.

Abstract

Monte Carlo calculations of the Ne K$\alpha$ line fluoresced by coronal x-rays and emitted near the temperature minimum region of the solar atmosphere have been employed to investigate the use of this feature to measure directly the solar photospheric Ne abundance. Though very weak, comparison with spectral line databases indicates that at plasma temperatures typical of the quiet Sun and cool active regions ($\leq 2\times 10^6$ K) the line is isolated and unblended. A canonical solar chemical composition yields an equivalent width of $\sim 6$ m\AA (0.3 eV) when observed at heliocentric angles $\sim 0$. For a 1 arcmin field of view, photon fluxes at Earth are of order 0.2 ph s$^{-1}$ for the quiet Sun, rendering the Ne K$\alpha$ fluorescent line a quite feasible means for determining the solar photospheric Ne content.