2021/01/07 by Deepak, David L. Lambert
Physics and Astronomy · #Asteroseismology #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Galaxy #Giant star #Lithium (medication) #Luminosity #Physics #Red giant #Stars #Stellar evolution #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stab1195
Updated Fig 4 and added comments about giants with unclassified evolutionary phase in our list. Also updated supplementary data in Zenodo (see https://zenodo.org/record/4519625 )
openalex publication_date 2021/01/07 · arxiv created 2021/05/06 · arxiv updated 2021/05/07 · openalex created_date 2021/05/10 · openalex updated_date 2026/08/05
In this study, we explore the evolution of lithium in giant stars based on data assembled from the literature on asteroseismology and Li abundances for giants. Our final sample of 187 giants consists of 44 red giant branch (RGB), 140 core He-burning (CHeB), and three giants with an unclassified evolutionary phase. For all 187 stars, the seismic parameters |ν \rm max| (frequency of maximum oscillation power) and Δν (large frequency spacing) are available, while |Δ Π \rm 1| (the asymptotic gravity-mode period spacing) is available for a subset of 64. For some of the CHeB giants, mass estimates from the asteroseismic scaling relations are found to be underestimated when compared with mass estimates from isochrones based on seismic data. Whilst most of the Li-rich giants in the sample have masses less than 1.5 M⊙, they are also present up to and beyond the maximum mass expected to have suffered a core He-flash, i.e. |M ≤| 2.25 M⊙: this suggests contributions from other processes towards Li enrichment. To understand the evolution of giants in the |Δ Π \rm 1 - Δ ν| plane, we use the Modules for Experiments in Stellar Astrophysics models that show the presence of mini-He-flashes following the initial strong core He-flash. From the distribution of A(Li) as a function of Δν, which is similar to the distribution of A(Li) as a function of luminosity, we find no indication of Li enrichment near the luminosity bump. Also, A(Li) trends to ∼−1.5 dex near the RGB tip. The data also suggest a decrease in A(Li) with an increase in |Δ Π \rm 1| for CHeB giants.