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Lithium depletion in solar-like stars : effect of overshooting based on realistic multi-dimensional simulations
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Baraffe, I., Pratt, J., Goffrey, Thomas, Constantino, T., Folini, D., Popov, M. V., Walder, R. and Viallet, M. (2017) Lithium depletion in solar-like stars : effect of overshooting based on realistic multi-dimensional simulations. Astrophysical Journal, 845 (1). L6. doi:10.3847/2041-8213/aa82ff
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Official URL: http://dx.doi.org/10.3847/2041-8213/aa82ff
Abstract
We study lithium depletion in low-mass and solar-like stars as a function of time, using a new diffusion coefficient describing extra-mixing taking place at the bottom of a convective envelope. This new form is motivated by multi-dimensional fully compressible, time-implicit 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 one-dimensional stellar evolution code, using parameters calibrated from multi-dimensional hydrodynamic simulations of a young low-mass 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 long-standing problem of lithium depletion in pre-main-sequence and main-sequence stars, the strength of our scenario is that its basic assumptions can be tested by future hydrodynamic simulations.
| Item Type: | Journal Article | ||||||||||
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| Subjects: | Q Science > QC Physics | ||||||||||
| Divisions: | Faculty of Science > Physics | ||||||||||
| Journal or Publication Title: | Astrophysical Journal | ||||||||||
| Publisher: | IOP Publishing | ||||||||||
| ISSN: | 0004-637X | ||||||||||
| Official Date: | 9 August 2017 | ||||||||||
| Dates: |
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| Volume: | 845 | ||||||||||
| Number: | 1 | ||||||||||
| Page Range: | L6 | ||||||||||
| DOI: | 10.3847/2041-8213/aa82ff | ||||||||||
| Status: | Peer Reviewed | ||||||||||
| Publication Status: | Published | ||||||||||
| Access rights to Published version: | Restricted or Subscription Access | ||||||||||
| Open Access Version: |
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