The solar oxygen crisis: probably not the last word

Abstract

In this work we present support for recent claims that advocate a downward revision of the solar oxygen abundance. Our analysis employs spatially resolved spectropolarimetric observations including the Fe I lines at 6302 Angstroms and the O I infrared triplet around 7774 Angstroms in the quiet Sun. We used the Fe I lines to reconstruct the three-dimensional thermal and magnetic structure of the atmosphere. The simultaneous O observations were then employed to determine the abundance of oxygen at each pixel, using both LTE and non-LTE (NLTE) approaches to the radiative transfer. In this manner, we obtain values of log e 8.63 (NLTE) and 8.93 (LTE) dex. We find an unsettling fluctuation of the oxygen abundance over the field of view. This is likely an artifact indicating that, even with this relatively refined strategy, important physical ingredients are still missing in the picture. By examining the spatial distribution of the abundance, we estimate realistic confidence limits of approximately 0.1 dex.