The GALAH survey: a census of lithium-rich giant stars

Martell, Sarah L. and Simpson, Jeffrey D. and Balasubramaniam, Adithya G. and Buder, Sven and Sharma, Sanjib and Hon, Marc and Stello, Dennis and Ting, Yuan-Sen and Asplund, Martin and Bland-Hawthorn, Joss and de Silva, Gayandhi M. and Freeman, Ken C. and Hayden, Michael and Kos, Janez and Lewis, Geraint F. and Lind, Karin and Zucker, Daniel B. and Zwitter, Tomaz and Campbell, Simon W. and Cotar, Klemen and Horner, Jonathan and Montet, Benjamin and Wittenmyer, Rob (2021) The GALAH survey: a census of lithium-rich giant stars. Monthly Notices of the Royal Astronomical Society, 505 (4). pp. 5340-5355. ISSN 0035-8711

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We investigate the properties of 1262 red giant stars with high photospheric abundances of lithium observed by the GALAH and K2-HERMES surveys, and discuss them in the context of proposed mechanisms for lithium enrichment and redepletion in giant stars. We confirm that Li-rich giants are rare, making up only 1.2 per cent of our giant star sample. We use stellar parameters from the third public data release from the GALAH survey and a Bayesian isochrone analysis to divide the sample into first-ascent red giant branch (RGB) and red clump (RC) stars, and confirm these classifications using asteroseismic data from K2. We find that RC stars are 2.5 times as likely to be lithium-rich as RGB stars, in agreement with other recent work. The probability for a star to be lithium-rich is affected by a number of factors, though the causality in those correlations is not entirely clear. We show for the first time that primary and secondary RC stars have distinctly different lithium enrichment patterns. The data set discussed here is large and heterogeneous in terms of evolutionary phase, metallicity, rotation rate, and mass. We expect that if the various mechanisms that have been proposed for lithium enrichment in evolved stars are in fact active, they should all contribute to this sample of lithium-rich giants at some level.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: C. 2021 The Author(s). Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 20 Jul 2021 01:38
Last Modified: 25 Oct 2021 23:57
Uncontrolled Keywords: stars; abundances; evolution; astrophysics; galaxies
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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