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.

arXiv comment10 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 (24)

• Gaia Data Release 2. Summary of the contents and survey properties
• Modules for Experiments in Stellar Astrophysics (MESA)
• Local stellar kinematics from Hipparcos data
• Elemental Abundance Survey of The Galactic Thick Disk
• Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars
• Gaia Data Release 2: first stellar parameters from Apsis
• The Primordial Lithium Problem
• The GALAH Survey: Second Data Release
• A Bitter Pill: The Primordial Lithium Problem Worsens
• Thermohaline instability and rotation-induced mixing. I - Low- and intermediate-mass solar metallicity stars up to the end of the AGB
• Red Giant Branch stars: the theoretical framework
• Period spacings in red giants II. Automated measurement
• Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013)
• Lithium Abundances of the Local Thin Disk Stars
• Origin of lithium enrichment in K giants
• Old puzzle, new insights: a lithium rich giant quietly burning helium in its core
• The Lithium Flash - Thermal instabilities generated by lithium burning in RGB stars
• On the red-giant luminosity bump
• White-dwarf red-giant mergers, early-type R stars, J stars and lithium
• Discovery of Super-Li Rich Red Giants in Dwarf Spheroidal Galaxies
• Two new Super Li-rich core He-burning giants: A new twist to the long tale of Li enhancement in K giants
• Spectroscopic study of two new super Li rich red clump K giants
• A new stellar mixing process operating below shell convection zones following off-center ignition
• The Gaia-ESO Survey: Inhibited extra mixing in two giants of the open cluster Trumpler 20?

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• Survey of Li-rich giants among Kepler and LAMOST fields: Determination of Li-rich giants Evolutionary Phase
• The GALAH survey: A census of lithium-rich giant stars
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• Enhancement of Lithium in Red Clump Stars by the Additional Energy Loss Induced by New Physics
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• Abundance analyses of Li-enriched and normal giants in the GALAH survey
• The Active Chromospheres of Lithium-Rich Red Giant Stars
• Hydrodynamics and survivability during post-main-sequence planetary engulfment
• Lithium abundances in giants as a function of stellar mass: An evidence for He-flash as the source of Li enhancement in low mass giants
• Lithium Evolution of Giant Stars Observed by LAMOST and Kepler
• Li-rich Giants in LAMOST Survey. III. The statistical analysis of Li-rich giants
• 7Be detection in the 2021 outburst of RS Oph
• Lithium abundances and asteroseismology of red giants: understanding the evolution of lithium in giants based on asteroseismic parameters
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• Lithium in red giants: the roles of the He-core flash and the luminosity bump
• An unsupervised method for identifying $X$-enriched stars directly from spectra: Li in LAMOST
• Probing infrared excess connection with Li enhancement among red clump giants
• Lithium in Kepler Red Giants: Defining Normal and Anomalous
• Li-rich Giants Identified from LAMOST DR8 Low-Resolution Survey
• Li-rich giant stars under scrutiny: Binarity, magnetic activity and the evolutionary status after Gaia DR2
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• On Lithium-6 as diagnostic of the lithium-enrichment mechanism in red giants
• Chemical Compositions of Red Giant Stars in the Old Open Cluster NGC 7789
• Convective Mixing: The Formation Channel of Li-rich Giants
• WIYN Open Cluster Study LXXXI. Caught in the Act? The Peculiar Red Giant NGC 2243-W2135
• Concerning Li-rich status of KIC~9821622: A Kepler field RGB star reported as Li-rich Giant