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The Gaia -ESO survey: Mixing processes in low-mass stars traced by lithium abundance in cluster and field stars

Magrini, L. ; Lagarde, N. ; Charbonnel, C. ; Franciosini, E. ; Randich, S. ; Smiljanic, R. ; Casali, G. ; Viscasillas Vázquez, C. ; Spina, L. and Biazzo, K. , et al. (2021) In Astronomy and Astrophysics 651.
Abstract

Aims. We aim to constrain the mixing processes in low-mass stars by investigating the behaviour of the Li surface abundance after the main sequence. We take advantage of the data from the sixth internal data release of Gaia-ESO, IDR6, and from the Gaia Early Data Release 3, EDR3s. Methods. We selected a sample of main-sequence, sub-giant, and giant stars in which the Li abundance is measured by the Gaia-ESO survey. These stars belong to 57 open clusters with ages from 130 Myr to about 7 Gyr and to Milky Way fields, covering a range in [Fe/H] between -1.0and +0.5 dex, with few stars between -1.0 and -2.5dex. We studied the behaviour of the Li abundances as a function of stellar parameters. We inferred the masses of giant stars in... (More)

Aims. We aim to constrain the mixing processes in low-mass stars by investigating the behaviour of the Li surface abundance after the main sequence. We take advantage of the data from the sixth internal data release of Gaia-ESO, IDR6, and from the Gaia Early Data Release 3, EDR3s. Methods. We selected a sample of main-sequence, sub-giant, and giant stars in which the Li abundance is measured by the Gaia-ESO survey. These stars belong to 57 open clusters with ages from 130 Myr to about 7 Gyr and to Milky Way fields, covering a range in [Fe/H] between -1.0and +0.5 dex, with few stars between -1.0 and -2.5dex. We studied the behaviour of the Li abundances as a function of stellar parameters. We inferred the masses of giant stars in clusters from the main-sequence turn-off masses, and for field stars through comparison with stellar evolution models using a maximum likelihood technique. We compared the observed Li behaviour in field giant stars and in giant stars belonging to individual clusters with the predictions of a set of classical models and of models with mixing induced by rotation and thermohaline instability. Results. The comparison with stellar evolution models confirms that classical models cannot reproduce the observed lithium abundances in the metallicity and mass regimes covered by the data. The models that include the effects of both rotation-induced mixing and thermohaline instability account for the Li abundance trends observed in our sample in all metallicity and mass ranges. The differences between the results of the classical models and of the rotation models largely differ (up to 2 dex), making lithium the best element with which to constrain stellar mixing processes in low-mass stars. We discuss the nature of a sample of Li-rich stars. Conclusions. We demonstrate that the evolution of the surface abundance of Li in giant stars is a powerful tool for constraining theoretical stellar evolution models, allowing us to distinguish the effect of different mixing processes. For stars with well-determined masses, we find a better agreement of observed surface abundances and models with rotation-induced and thermohaline mixing. Rotation effects dominate during the main sequence and the first phases of the post-main-sequence evolution, and the thermohaline induced mixing after the bump in the luminosity function.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Open clusters and associations: general, Stars: abundances, Stars: evolution
in
Astronomy and Astrophysics
volume
651
article number
A84
publisher
EDP Sciences
external identifiers
  • scopus:85111162641
ISSN
0004-6361
DOI
10.1051/0004-6361/202140935
language
English
LU publication?
yes
id
fd24124d-76ff-4b3a-9ee4-dd19f272c376
date added to LUP
2022-03-29 09:39:05
date last changed
2024-04-10 09:18:28
@article{fd24124d-76ff-4b3a-9ee4-dd19f272c376,
  abstract     = {{<p>Aims. We aim to constrain the mixing processes in low-mass stars by investigating the behaviour of the Li surface abundance after the main sequence. We take advantage of the data from the sixth internal data release of Gaia-ESO, IDR6, and from the Gaia Early Data Release 3, EDR3s. Methods. We selected a sample of main-sequence, sub-giant, and giant stars in which the Li abundance is measured by the Gaia-ESO survey. These stars belong to 57 open clusters with ages from 130 Myr to about 7 Gyr and to Milky Way fields, covering a range in [Fe/H] between -1.0and +0.5 dex, with few stars between -1.0 and -2.5dex. We studied the behaviour of the Li abundances as a function of stellar parameters. We inferred the masses of giant stars in clusters from the main-sequence turn-off masses, and for field stars through comparison with stellar evolution models using a maximum likelihood technique. We compared the observed Li behaviour in field giant stars and in giant stars belonging to individual clusters with the predictions of a set of classical models and of models with mixing induced by rotation and thermohaline instability. Results. The comparison with stellar evolution models confirms that classical models cannot reproduce the observed lithium abundances in the metallicity and mass regimes covered by the data. The models that include the effects of both rotation-induced mixing and thermohaline instability account for the Li abundance trends observed in our sample in all metallicity and mass ranges. The differences between the results of the classical models and of the rotation models largely differ (up to 2 dex), making lithium the best element with which to constrain stellar mixing processes in low-mass stars. We discuss the nature of a sample of Li-rich stars. Conclusions. We demonstrate that the evolution of the surface abundance of Li in giant stars is a powerful tool for constraining theoretical stellar evolution models, allowing us to distinguish the effect of different mixing processes. For stars with well-determined masses, we find a better agreement of observed surface abundances and models with rotation-induced and thermohaline mixing. Rotation effects dominate during the main sequence and the first phases of the post-main-sequence evolution, and the thermohaline induced mixing after the bump in the luminosity function. </p>}},
  author       = {{Magrini, L. and Lagarde, N. and Charbonnel, C. and Franciosini, E. and Randich, S. and Smiljanic, R. and Casali, G. and Viscasillas Vázquez, C. and Spina, L. and Biazzo, K. and Pasquini, L. and Bragaglia, A. and Van Der Swaelmen, M. and Tautvaišienė, G. and Inno, L. and Sanna, N. and Prisinzano, L. and Degl'Innocenti, S. and Prada Moroni, P. and Roccatagliata, V. and Tognelli, E. and Monaco, L. and De Laverny, P. and Delgado-Mena, E. and Baratella, M. and D'Orazi, V. and Vallenari, A. and Gonneau, A. and Worley, C. and Jiménez-Esteban, F. and Jofre, P. and Bensby, T. and François, P. and Guiglion, G. and Bayo, A. and Jeffries, R. D. and Binks, A. S. and Gilmore, G. and Damiani, F. and Korn, A. and Pancino, E. and Sacco, G. G. and Hourihane, A. and Morbidelli, L. and Zaggia, S.}},
  issn         = {{0004-6361}},
  keywords     = {{Open clusters and associations: general; Stars: abundances; Stars: evolution}},
  language     = {{eng}},
  month        = {{07}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{The Gaia -ESO survey: Mixing processes in low-mass stars traced by lithium abundance in cluster and field stars}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/202140935}},
  doi          = {{10.1051/0004-6361/202140935}},
  volume       = {{651}},
  year         = {{2021}},
}