SIMBAD references

The fraction of light removed from a star's spectrum by the spectral lines, the line absorption, is shown to be a precise empirical indicator of metallicity. We measured the line absorption in 89 class III giant stars in a 42.5 Å window between 6219.0 and 6261.5 Å and then calibrated these values against published metallicities. We show that the line absorption can be measured precisely enough to improve the metallicity precision about fivefold over the original calibration metallicities, reaching a precision of 0.01 dex in favorable cases.