Lithium Depletion in Solarlike Stars: Effect of Overshooting Based on Realistic Multidimensional Simulations
Abstract
We study lithium depletion in lowmass and solarlike stars as a function of time, using a new diffusion coefficient describing extramixing taking place at the bottom of a convective envelope. This new form is motivated by multidimensional fully compressible, timeimplicit hydrodynamic simulations performed with the MUSIC code. Intermittent convective mixing at the convective boundary in a star can be modeled using extreme value theory, a statistical analysis frequently used for finance, meteorology, and environmental science. In this Letter, we implement this statistical diffusion coefficient in a onedimensional stellar evolution code, using parameters calibrated from multidimensional hydrodynamic simulations of a young lowmass star. We propose a new scenario that can explain observations of the surface abundance of lithium in the Sun and in clusters covering a wide range of ages, from ∼50 Myr to ∼4 Gyr. Because it relies on our physical model of convective penetration, this scenario has a limited number of assumptions. It can explain the observed trend between rotation and depletion, based on a single additional assumption, namely, that rotation affects the mixing efficiency at the convective boundary. We suggest the existence of a threshold in stellar rotation rate above which rotation strongly prevents the vertical penetration ofmore »
 Authors:
 Astrophysics Group, University of Exeter, Exeter EX4 4QL (United Kingdom)
 Ecole Normale Supérieure de Lyon, CRAL, UMR CNRS 5574, F69364 Lyon Cedex 07 (France)
 Publication Date:
 OSTI Identifier:
 22654414
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Astrophysical Journal Letters; Journal Volume: 845; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CONVECTION; DIFFUSION; EFFICIENCY; HYDRODYNAMICS; LITHIUM; ONEDIMENSIONAL CALCULATIONS; ROTATION; SIMULATION; STAR EVOLUTION; SURFACES; TIME DEPENDENCE
Citation Formats
Baraffe, I., Pratt, J., Goffrey, T., Constantino, T., Viallet, M., Folini, D., Popov, M. V., and Walder, R., Email: i.baraffe@ex.ac.uk. Lithium Depletion in Solarlike Stars: Effect of Overshooting Based on Realistic Multidimensional Simulations. United States: N. p., 2017.
Web. doi:10.3847/20418213/AA82FF.
Baraffe, I., Pratt, J., Goffrey, T., Constantino, T., Viallet, M., Folini, D., Popov, M. V., & Walder, R., Email: i.baraffe@ex.ac.uk. Lithium Depletion in Solarlike Stars: Effect of Overshooting Based on Realistic Multidimensional Simulations. United States. doi:10.3847/20418213/AA82FF.
Baraffe, I., Pratt, J., Goffrey, T., Constantino, T., Viallet, M., Folini, D., Popov, M. V., and Walder, R., Email: i.baraffe@ex.ac.uk. 2017.
"Lithium Depletion in Solarlike Stars: Effect of Overshooting Based on Realistic Multidimensional Simulations". United States.
doi:10.3847/20418213/AA82FF.
@article{osti_22654414,
title = {Lithium Depletion in Solarlike Stars: Effect of Overshooting Based on Realistic Multidimensional Simulations},
author = {Baraffe, I. and Pratt, J. and Goffrey, T. and Constantino, T. and Viallet, M. and Folini, D. and Popov, M. V. and Walder, R., Email: i.baraffe@ex.ac.uk},
abstractNote = {We study lithium depletion in lowmass and solarlike stars as a function of time, using a new diffusion coefficient describing extramixing taking place at the bottom of a convective envelope. This new form is motivated by multidimensional fully compressible, timeimplicit hydrodynamic simulations performed with the MUSIC code. Intermittent convective mixing at the convective boundary in a star can be modeled using extreme value theory, a statistical analysis frequently used for finance, meteorology, and environmental science. In this Letter, we implement this statistical diffusion coefficient in a onedimensional stellar evolution code, using parameters calibrated from multidimensional hydrodynamic simulations of a young lowmass star. We propose a new scenario that can explain observations of the surface abundance of lithium in the Sun and in clusters covering a wide range of ages, from ∼50 Myr to ∼4 Gyr. Because it relies on our physical model of convective penetration, this scenario has a limited number of assumptions. It can explain the observed trend between rotation and depletion, based on a single additional assumption, namely, that rotation affects the mixing efficiency at the convective boundary. We suggest the existence of a threshold in stellar rotation rate above which rotation strongly prevents the vertical penetration of plumes and below which rotation has small effects. In addition to providing a possible explanation for the longstanding problem of lithium depletion in premainsequence and mainsequence stars, the strength of our scenario is that its basic assumptions can be tested by future hydrodynamic simulations.},
doi = {10.3847/20418213/AA82FF},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 845,
place = {United States},
year = 2017,
month = 8
}

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