Study of Lithium Rich Giants with the GALAH Spectroscopic Survey

Abstract

In this article, we speculate on the possible mechanisms for Li enhancement origin in RGB stars based on a large data set of around 340,299 stars collected from the GALAH survey combined with the Gaia astrometry. Data has 51,982 low mass (M$\le$ 2M${}_{\odot }$) RGB stars with reliable atmospheric parameters. The data set shows a well populated RGB with well-defined luminosity bump and red clump with significant number of stars at each of these two key phases. We found 335 new Li-rich RGB stars with Li abundance, A(Li) $\ge$ 1.80 $\pm$ 0.14 dex, of which 20 are super Li-rich with A(Li) $\ge$ 3.20~dex. Most of them appear to be in the red clump region which, when combined with stellar evolutionary timescales on RGB, indicates that the Li enhancement origin may lie at RGB tip during He-flash rather than by external source of merging of sub-stellar objects or during luminosity bump evolution. Kinematic properties of sample stars suggest that Li-rich giants are relatively more prevalent among giants of thin disk compared to thick disk and halo.

10 pages (+6 pages of supplementary data table), 6 figures, 2 tables, accepted for publication in Monthly Notices of the Royal Astronomical Society on January 10, 2019

References in corpus (6)

• Modules for Experiments in Stellar Astrophysics (MESA)
• The Primordial Lithium Problem
• A Bitter Pill: The Primordial Lithium Problem Worsens
• Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013)
• White-dwarf red-giant mergers, early-type R stars, J stars and lithium
• Discovery of Super-Li Rich Red Giants in Dwarf Spheroidal Galaxies

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