A revision of the solar manganese abundance using new and remeasured laboratory oscillator strengths

Abstract

Context. The solar photospheric element abundances are generally in good agreement with the meteoritic CI chondrite abundances, with the exception of a small number of elements including manganese. The solar photospheric abundances, determined using model atmospheres, include laboratory oscillator strengths where available. However, the current laboratory database for Mn i oscillator strengths is derived from several different laboratory observations determined from several different laboratory techniques. The uncertainty in the solar photospheric manganese abundance and the difference between it and the meteoritic CI chondrite abundance may just be an artefact of inaccurate laboratory data. Aims. The aim of our new laboratory measurements is to measure a self consistent set of accurate absolute oscillator strengths and use the new laboratory data to re-evaluate the solar manganese abundance. Methods. New and more accurate oscillator strengths have been determined by combining branching fractions with previously measured energy level lifetimes. Using the new laboratory data, the solar photospheric abundance of manganese has been determined with theoretical and semi-empirical model atmospheres, MAFAGS-ODF and Holweger & Müller, respectively.Results. We present experimental oscillator strengths for 94 Mn i transitions covering the wavelength range 2384 to 17 744 Å. Using 22 relatively un-blended solar Mn i transitions, we determine the photospheric abundance of manganese to be log ε = 5.37±0.05 dex. Conclusions.The new value is in good agreement with previous photospheric abundance determinations. The implications for the solar photospheric and meteoritic CI chondrite abundance is discussed.

The elemental composition of the Sun

“…Whilst we expect both sets to be reliable, the g f -values of Booth et al (1984a) are consistently ∼0.15-0.20 dex higher than the GW-Becker et al or GW-Schnabel et al values. This is confirmed when the g f -values of Blackwell-Whitehead & Bergemann (2007) are compared with the data of Booth et al (1984a): the values of Booth et al are systematically larger, by 0.13 dex (±0.02). This is however not the case for the 2 eV system, where the two sets agree very well.…”

“…Wherever possible, we use the oscillator strengths of Blackwell-Whitehead & Bergemann (2007) or those recommended by Den Hartog et al (2011). In cases of overlap, we use the recommended Den Schnabel et al (1995).…”

“…Mn has just a single stable isotope (Rosman & Taylor 1998) Blackwell-Whitehead & Bergemann (2007) and Blackwell-Whitehead et al (2005b). Blackwell-Whitehead & Bergemann (2007) used highly accurate TRLIF lifetimes from Schnabel et al (1995), along with one other lifetime from the laser-excited delayed coincidence of Marek (1975) to produce accurate oscillator strengths.…”

“…Mn has just a single stable isotope (Rosman & Taylor 1998) Blackwell-Whitehead & Bergemann (2007) and Blackwell-Whitehead et al (2005b). Blackwell-Whitehead & Bergemann (2007) used highly accurate TRLIF lifetimes from Schnabel et al (1995), along with one other lifetime from the laser-excited delayed coincidence of Marek (1975) to produce accurate oscillator strengths. Blackwell-Whitehead et al (2005b) used their own TRLIF lifetimes to also convert their BFs into accurate oscillator strengths, though for some levels slightly more accurate TRLIF lifetimes are also available from Schnabel et al (1995).…”

“…Their analysis with the MAFAGS-ODF model produced an abundance of log Mn = 5.36 ± 0.10. This work was subsequently revised with improved oscillator strengths by Blackwell-Whitehead & Bergemann (2007), giving log Mn = 5.37 ± 0.05 with the same model. Using the HM model, the result was log Mn = 5.46 ± 0.08, in reasonable agreement with the meteoritic value but exhibiting an uncomfortably high scatter.…”