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The Gaia-ESO Survey: revisiting the Li-rich giant problem

Casey, AR and Ruchti, G and Masseron, T and Randich, S and Gilmore, G and Lind, K and Kennedy, GM and Koposov, SE and Hourihane, A and Franciosini, E and Lewis, JR and Magrini, L and Morbidelli, L and Sacco, GG and Worley, CC and Feltzing, S and Jeffries, RD and Vallenari, A and Bensby, T and Bragaglia, A and Flaccomio, E and Francois, P and Korn, AJ and Lanzafame, A and Pancino, E and Recio-Blanco, A and Smiljanic, R and Carraro, G and Costado, MT and Damiani, F and Donati, P and Frasca, A and Jofre, P and Lardo, C and de Laverny, P and Monaco, L and Prisinzano, L and Sbordone, L and Sousa, SG and Tautvaisiene, G and Zaggia, S and Zwitter, T and Delgado Mena, E and Chorniy, Y and Martell, SL and Aguirre, VS and Miglio, A and Chiappini, C and Montalban, J and Morel, T and Valentini, M (2016) The Gaia-ESO Survey: revisiting the Li-rich giant problem. Monthly Notices of the Royal Astronomical Society, 461 (3). pp. 3336-3352. ISSN 0035-8711

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Abstract

The discovery of lithium-rich giants contradicts expectations from canonical stellar evolution. Here we report on the serendipitous discovery of 20 Li-rich giants observed during the Gaia-ESO Survey, which includes the _rst nine Li-rich giant stars known towards the CoRoT _elds. Most of our Li-rich giants have near-solar metallicities, and stellar parameters consistent with being before the luminosity bump. This is di_cult to reconcile with deep mixing models proposed to explain lithium enrichment, because these models can only operate at later evolutionary stages: at or past the luminosity bump. In an e_ort to shed light on the Li-rich phenomenon, we highlight recent evidence of the tidal destruction of close-in hot Jupiters at the sub-giant phase. We note that when coupled with models of planet accretion, the observed destruction of hot Jupiters actually predicts the existence of Li-rich giant stars, and suggests Li-rich stars should be found early on the giant branch and occur more frequently with increasing metallicity. A comprehensive review of all known Li-rich giant stars reveals that this scenario is consistent with the data. However more evolved or metal-poor stars are less likely to host close-in giant planets, implying that their Li-rich origin requires an alternative explanation, likely related to mixing scenarios rather than external phenomena.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
Related URLs:
Date Deposited: 22 Nov 2016 11:50
Last Modified: 08 Sep 2017 02:22
DOI or Identification number: 10.1093/mnras/stw1512
URI: http://researchonline.ljmu.ac.uk/id/eprint/4834

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