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

Casey, AR, Ruchti, G, Masseron, T, Randich, S, Gilmore, G, Lind, K, Kennedy, GM, Koposov, SE, Hourihane, A, Franciosini, E, Lewis, JR, Magrini, L, Morbidelli, L, Sacco, GG, Worley, CC, Feltzing, S, Jeffries, RD, Vallenari, A, Bensby, T, Bragaglia, A , Flaccomio, E, Francois, P, Korn, AJ, Lanzafame, A, Pancino, E, Recio-Blanco, A, Smiljanic, R, Carraro, G, Costado, MT, Damiani, F, Donati, P, Frasca, A, Jofre, P, Lardo, C, de Laverny, P, Monaco, L, Prisinzano, L, Sbordone, L, Sousa, SG, Tautvaisiene, G, Zaggia, S, Zwitter, T, Delgado Mena, E, Chorniy, Y, Martell, SL, Aguirre, VS, Miglio, A, Chiappini, C, Montalban, J, 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: 04 Sep 2018 23:07
DOI or Identification number: 10.1093/mnras/stw1512
URI: http://researchonline.ljmu.ac.uk/id/eprint/4834

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