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A Li-rich red giant star (2M19411367+4003382) recently discovered in thedirection of NGC 6819 belongs to the rare subset of Li-rich stars that have notyet evolved to the luminosity bump, an evolutionary stage where models predictLi can be replenished. The currently favored model to explain Li enhancement infirst-ascent red giants like 2M19411367+4003382 requires deep mixing into thestellar interior. Testing this model requires a measurement of 12C/13C, whichis possible to obtain from APOGEE spectra. However, the Li-rich star also hasabnormal asteroseismic properties that call into question its membership in thecluster, even though its radial velocity and location on color-magnitudediagrams are consistent with membership. To address these puzzles, we havemeasured a wide array of abundances in the Li-rich star and three comparisonstars using spectra taken as part of the APOGEE survey to determine the degreeof stellar mixing, address the question of membership, and measure the surfacegravity. We confirm that the Li-rich star is a red giant with the same overallchemistry as the other cluster giants. However, its log g is significantlylower, consistent with the asteroseismology results and suggestive of a verylow mass if the star is indeed a cluster member. Regardless of the clustermembership, the 12C/13C and C/N ratios of the Li-rich star are consistent withstandard first dredge-up, indicating that Li dilution has already occurred, andinconsistent with internal Li enrichment scenarios that require deep mixing.

The Puzzling Li-rich Red Giant Associated with NGC 6819