Neon and Oxygen Absolute Abundances in the Solar Corona

Abstract

In the present work we use the UV spectrum of a solar flare observedwith SOHO SUMER to measure the absolute abundance of Ne in the solaratmosphere. The measurement is carried out using the intensity ratiobetween the allowed 1s2s S-3(1)-1s2p P-3(2) Ne ix line at 1248.28angstrom and the free-free continuum radiation observed close tothe Ne ix line. We find a value of the absolute Ne abundance A(Ne)= 8.11 +/- 0.12, in agreement with previous estimates but substantiallyhigher than the very recent estimate by Asplund et al. based on theoxygen photospheric abundance and the Ne/O relative abundance. Consideringour measured A(Ne) value, we argue that the absolute oxygen abundanceof Asplund et al. is too low by a factor 1.9. This result has importantconsequences for models of the solar interior based on helioseismologymeasurements, as well as on the FIP bias determination of the solarupper atmosphere, solar wind, and solar energetic particles.