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

Casey, A. R.; Ruchti, G. LU ; Masseron, T.; Randich, S.; Gilmore, G.; Lind, K.; Kennedy, G. M.; Koposov, S. E.; Hourihane, A. and Franciosini, E., et al. (2016) In Monthly Notices of the Royal Astronomical Society 461(3). p.3336-3352
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 first nine Li-rich giant stars known towards the CoRoT fields. Most of our Li-rich giants have near-solar metallicities and stellar parameters consistent with being before the luminosity bump. This is difficult 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 effort to shed light on the Li-rich phenomenon, we highlight recent evidence of the tidal destruction of close-in hot Jupiters at the... (More)

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 first nine Li-rich giant stars known towards the CoRoT fields. Most of our Li-rich giants have near-solar metallicities and stellar parameters consistent with being before the luminosity bump. This is difficult 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 effort 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 that 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.

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publication status
published
subject
keywords
Abundances, Stars
in
Monthly Notices of the Royal Astronomical Society
volume
461
issue
3
pages
17 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:84983792817
  • wos:000383481100076
ISSN
0035-8711
DOI
10.1093/mnras/stw1512
language
English
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yes
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51c66471-2e7b-4460-9c88-189b4e525b15
date added to LUP
2016-11-02 14:29:30
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2017-10-03 10:27:01
@article{51c66471-2e7b-4460-9c88-189b4e525b15,
  abstract     = {<p>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 first nine Li-rich giant stars known towards the CoRoT fields. Most of our Li-rich giants have near-solar metallicities and stellar parameters consistent with being before the luminosity bump. This is difficult 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 effort 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 that 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.</p>},
  articleno    = {stw1512},
  author       = {Casey, A. R. and Ruchti, G. and Masseron, T. and Randich, S. and Gilmore, G. and Lind, K. and Kennedy, G. M. and Koposov, S. E. and Hourihane, A. and Franciosini, E. and Lewis, J. R. and Magrini, L. and Morbidelli, L. and Sacco, G. G. and Worley, C. C. and Feltzing, S. and Jeffries, R. D. and Vallenari, A. and Bensby, T. and Bragaglia, A. and Flaccomio, E. and Francois, P. and Korn, A. J. and Lanzafame, A. and Pancino, E. and Recio-Blanco, A. and Smiljanic, R. and Carraro, G. and Costado, M. T. and Damiani, F. and Donati, P. and Frasca, A. and Jofré, P. and Lardo, C. and de Laverny, P. and Monaco, L. and Prisinzano, L. and Sbordone, L. and Sousa, S. G. and Tautvaišiene, G. and Zaggia, S. and Zwitter, T. and Mena, E. Delgado and Chorniy, Y. and Martell, S. L. and Aguirre, V. Silva and Miglio, A. and Chiappini, C. and Montalban, J. and Morel, T. and Valentini, M.},
  issn         = {0035-8711},
  keyword      = {Abundances,Stars},
  language     = {eng},
  month        = {09},
  number       = {3},
  pages        = {3336--3352},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {The Gaia-ESO Survey : Revisiting the Li-rich giant problem},
  url          = {http://dx.doi.org/10.1093/mnras/stw1512},
  volume       = {461},
  year         = {2016},
}