Poster Abstracts

Name/Affiliation:  Joleen Carlberg (Carnegie Institution of Washington)

Title:  Lithium Inventory of 2 M_sun Red Clump Stars: Is Li created during the He Flash?

Abstract:
Recent studies of Li abundances in field red giant stars have suggested that the phenomenon of enriched surface Li may be a short-lived phase of red clump evolution for stars with masses near 2 M_sun. Although the exact mechanism for generating this Li is not fully understood, it may be related to the He-core flash that immediately precedes the red clump stage. To test the incidence and timescale of this proposed process, we are targeting ~25 red clump stars in four southern open clusters, using the cluster ages to ensure that the stellar masses are ~2 M_sun. Additionally, we observe at least one upper red giant branch star in each cluster to establish the baseline Li abundance prior to the He flash. Here, we present results for the three clusters observed to date. None of the stars are Li-rich according to the usual criterion (A(Li) > 1.5 dex), but at least one red clump star shows moderate Li enrichment compared to the other stars in the cluster, suggesting that it may have passed through a more Li-rich stage.