Metallicity indices in open clusters

Observations of field giants of known metallicity provide a correlation between the spectroscopic indices and the metallicity of open cluster giants. We use 2 analysis to fit the relation of spectrophotometric indices to metallicity in field giants.

The resulting function allows an estimate of the target-cluster giants' metallicities with an error in the method of +/-0.08 dex. We derive the following metallicities for the seven open clusters: NGC 1245, [M/H]=-0.14+/-0.04; NGC 2099, [M/H]=+0.05+/-0.05; NGC 2324, [M/H]=-0.06+/-0.04; NGC 2539, [M/H]=-0.04+/-0.03; NGC 2682 (M67), [M/H]=-0.05+/-0.02; NGC 6705, [M/H]=+0.14+/-0.08; NGC 6819, [M/H]=-0.07+/-0.12. These metallicity estimates will be useful in planning future extrasolar planet transit searches, since planets may form more readily in metal-rich environments.