Lithium-rich giants in GALAH DR3
Around one percent of evolved stars are surprisingly rich in lithium, and the fraction rises with rising metallicity. Lithium is destroyed by proton capture at relatively low temperature, and in standard stellar evolution models it is depleted significantly in post-main-sequence evolution. A number of mechanisms have been proposed as the source of lithium in giant stars, based on their rareness and their tendency to be found near the red clump and the "bump" in the red giant branch luminosity function. However, uncertainty about the evolutionary stages of stars near the RC in the log(g)-Teff plane makes it difficult to evaluate these mechanisms. While there are five Li-rich giants currently known in the Kepler field, only three have sufficient Kepler data for asteroseismic classification, and two of those are anomalous in other ways.
We have identified nearly 2000 Li-rich giants in GALAH iDR3, and we will use asteroseismic RC vs RGB classifications for K2 where available. We will evaluate the consistency of various models for Li production with this data set, and revisit the observational features that are sometimes observed along with Li enrichment, such as rapid rotation and infrared excess. We will also investigate the orbital dynamics of Li-rich giants as a group and as sub-populations, which has not been done before.
Current participants: Sarah Martell, Jeffrey Simpson, Dennis Stello, John Lattanzio, Simon Campbell Additional participants welcome.
