Possible Identification of a Metal-Rich Old Moving Group: High-Resolution Spectroscopy of Candidate Members

Using new high-resolution spectroscopic observations from both the McDonald Observatory 2.7 m and Kitt Peak National Observatory 4 m telescopes, we observed four candidate members of the Ursa Major moving group previously suggested to instead belong to a significantly older kinematic assemblage. The Fe abundances we measure strongly suggest that these stars are not UMa members but form a more metal-rich group of stars (+0.10 ≤ [Fe/H] ≤ +0.18) with an age near 3 Gyr. Our [Ca/H] determinations corroborate this result. The apparent similarities in metallicity and previously discovered UVW space motions lend credence to prior suggestions that these stars belong to a field kinematic structure of uniform age. Li abundances have also been derived from the 6707 Å feature for all four stars and show the differences expected from the stars\u27 varying evolutionary states. The low Li abundance of one object, HD 88654, does not support its previously reported status as a post-T Tauri star candidate