Comparison of Standard Solar Compositions

T. Do

The standard solar composition was updated in Grevesse, Asplund, & Sauval 2007 (GAS07), which has significantly lower abundances for some elements compared to the previous reference Grevesse & Sauval 1998 (GS98). However, many papers still report abundance measurements such as [Fe/H] relative to GS98. For example, Fe in GAS07 is 0.05 dex lower than in GS98. In order to facilitate correction for abundance measurements between GS98 and GAS07, the following are excerpts from the tables of elemental abundances.

The abundance of an element is relative to hydrogen as defined by: A_el = log_N_el/N_H +12.0 (e.g. hydrogen is defined as A_H = 12.0). The following table shows the photospheric values from the two references.

Element A_el (GAS07) A_el (GS98)
H 12.0 12.0
He 10.93 +- 0.01 10.93 +- 0.004
Li 1.05 +- 0.10 1.10 +- 0.10
C 8.39 +- 0.05 8.52 +- 0.06
N 7.78 +- 0.06 7.92 +- 0.06
O 8.66 +- 0.05 8.83 +- 0.06
Na 6.17 +- 0.04 6.36 +- 0.02
Ca 6.31 +- 0.04 8.83 +- 0.06
Fe 7.45 +- 0.05 7.50 +- 0.05

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