WIYN Open Cluster Study: Spectroscopic Abundances of M34 from the Oxygen Triplet Region

Oxygen has been suggested as a superior chronometer to iron for studying Galactic chemical evolution. Open clusters are an ideal tool for studying abundance-age relationships, given their knowable age and uniform chemical composition. As part of a larger study to investigate the O-age relationship found by King (1993) we obtained high-resolution spectra of the oxygen triplet region for 49 candidate dwarf members in M34, age 225 Myr, using the HYDRA multi-object spectrometer on the WIYN 3.5m. The following results are based on the 38 of these 49 candidate members that turned out to be slowly-rotating single-star radial velocity members. We report weighted cluster average abundances of [Fe/H] = 0.16 ± 0.03, [O/H] = 0.06 ± 0.06, [Al/H] = -0.02 ± 0.02, [Ni/H] = 0.36 ± 0.02, and [Si/H] = -0.01 ± 0.01. Each error includes two components added in quadrature: one component is simply the standard deviation of the mean of all the cluster lines included in the average, and the other component is related to the standard deviation of the mean in the Teff, for each star, that arises from the use of multiple color indices for the derivation of Teff. Our low [O/Fe] is inconsistent with the supersolar [O/Fe] suggested by King for young clusters.