Kavli Affiliate: Anna Frebel
| First 5 Authors: Jeremy Kowkabany, Rana Ezzeddine, Corinne Charbonnel, Ian U. Roederer, Ella Xi Wang
| Summary:
We present the discovery of 2MASS J05241392-0336543 (hereafter J0524-0336), a
very metal-poor ([Fe/H]=-2.43 +- 0.16), highly r-process-enhanced ([Eu/Fe]=
+1.34 +- 0.10) Milky Way halo field red giant star, with an ultra high Li
abundance of A(Li)(3D,NLTE)= 6.15 +- 0.25 and [Li/Fe]= +7.64 +- 0.25,
respectively. This makes J0524-0336 the most lithium-enhanced giant star
discovered to date. We present a detailed analysis of the star’s atmospheric
stellar parameters and chemical abundance determinations. Additionally, we
detect indications of infrared excess, as well as observe variable emission in
the wings of the H_alpha absorption line across multiple epochs, indicative of
a potential enhanced mass-loss event with possible outflows. Our analysis
reveals that J0524-0336 lies either between the bump and the tip of the Red
Giant Branch (RGB), or on the early-Asymptotic Giant Branch (e-AGB). We
investigate the possible sources of lithium enrichment in J0524-0336, including
both internal and external sources. Based on current models and on the
observational evidence we have collected, our study shows that J0524-0336 may
be undergoing the so-called lithium flash that is expected to occur in low-mass
stars when they reach the RGB bump and/or the early-AGB.
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