HD 77361: a new case of super Li-rich K giant with anomalous low C-12/C-13 ratio

Abstract

Results from high-resolution spectroscopic analysis of HD77361 are reported. LTE analysis shows that HD77361 is a K giant of atmospheric parameters: T-eff = 4580 +/- 75 K, log g = 2.5 +/- 0.1, and xi(t) = 1.40 +/- 0.5 km s(-1). We found that the atmosphere of HD 77361 is highly enriched in Li with log epsilon (Li) = 3.82 +/- 0.1. With this finding the total number of super Li-rich K giants (log epsilon(Li) >= 3.3 ISM value) known to date reached six. Contrary to first dredge-up, extra-deep mixing and the associated cool bottom processing, and other recent predictions for K giants on the red giant branch (RGB) luminosity bump phase, HD 77361 shows a very low value of C-12/C-13 = 4.3 +/- 0.5, having, simultaneously, very large amount of Li. Also, HD 77361 is the only Population I low-luminosity (log L/L-circle dot = 1.66 +/- 0.1) low-mass K giant (M = 1.5 +/- 0.2 M-circle dot) among the known super Li-rich K giants that has a very low C-12/C-13 ratio. Results of HD 77361 further constrain our theoretical understanding of Li enhancement in the atmospheres of RGB stars.