Concerning the Li-rich status of KIC 9821622: a Kepler field RGB star reported as a Li-rich giant. Issue 3 (13th December 2019)

• Record Type: Journal Article
• Authors: Singh, Raghubar; Bharat Kumar, Yerra; Reddy, Bacham E; Aoki, Wako
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 491:Issue 3(2020)
• Page Start: 3838
• Page End: 3843
• Publication Date: 2019-12-13
• Subjects: stars: abundances -- stars: evolution -- stars: fundamental parameters -- stars: low-mass; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz3222
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Given the implications for the origin of Li enhancement in red giants, we have reviewed the Li-rich classification of KIC 9821622, the only bonafide red giant branch (RGB) giant with a He inert core to date, reported as a Li-rich giant by reanalysing the high-resolution spectra. We have obtained A (Li)LTE = 1.42 ± 0.05 dex. After correcting for non-local thermodynamic equilibrium (NLTE), we have A (Li)NLTE = 1.57 ± 0.05 dex, which is significantly less than the reported A (Li) = 1.80 ± 0.2 dex. We found that the subordinate line at 6103 Å is too weak or absent to measure Li abundance. The derived abundance is normal for red giants undergoing dilution during the first dredge-up. Since all known Kepler field Li-rich giants belong to the red clump region, this clarification removes the anomaly and strengthens the evidence that Li enhancement in low-mass giants may be associated only with the He-core burning phase. The origin of Li excess probably lies during the He flash at the RGB tip, a phase immediately preceding the red clump.