Document Type

Article

Publication Date

4-2007

Publication Title

The Astronomical Journal

Volume

133

Issue

6

Publisher

The American Astronomical Society

Abstract

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' 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.

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