Lithium abundance derived in metal-poor main-sequence (MS) stars is about three times lower than the value of primordial Li predicted by the standard big bang nucleosynthesis when the baryon density is taken from the cosmic microwave background or the deuterium measurements. This disagreement is generally referred as the lithium problem. We here reconsider the stellar Li evolution from the pre-main sequence (PMS) to the end of the MS phase by introducing the effects of convective overshooting (OV) and residual mass accretion. We show that Li-7 could be significantly depleted by convective OV in the PMS phase and then partially restored in the stellar atmosphere by a tail of matter accretion which follows the Li-depletion phase and that could be regulated by EUV photoevaporation. By considering the conventional nuclear burning and microscopic diffusion along the MS, we can reproduce the Spite plateau for stars with initial mass m(0) = 0.62-0.80 M-circle dot, and the Li declining branch for lower mass dwarfs, e.g. m(0) = 0.57-0.60 M-circle dot, for a wide range of metallicities (Z = 0.00001 to Z = 0.0005), starting from an initial Li abundance A(Li) = 2.72. This environmental Li evolution model also offers the possibility to interpret the decrease of Li abundance in extremely metal-poor stars, the Li disparities in spectroscopic binaries and the low Li abundance in planet hosting stars.

Lithium evolution in metal-poor stars: from pre-main sequence to the Spite plateau / Fu, Xiaoting; Bressan, Alessandro; Molaro, Paolo; Marigo, Paola. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 452:3(2015), pp. 3256-3265. [10.1093/mnras/stv1384]

Lithium evolution in metal-poor stars: from pre-main sequence to the Spite plateau

Bressan, Alessandro;
2015-01-01

Abstract

Lithium abundance derived in metal-poor main-sequence (MS) stars is about three times lower than the value of primordial Li predicted by the standard big bang nucleosynthesis when the baryon density is taken from the cosmic microwave background or the deuterium measurements. This disagreement is generally referred as the lithium problem. We here reconsider the stellar Li evolution from the pre-main sequence (PMS) to the end of the MS phase by introducing the effects of convective overshooting (OV) and residual mass accretion. We show that Li-7 could be significantly depleted by convective OV in the PMS phase and then partially restored in the stellar atmosphere by a tail of matter accretion which follows the Li-depletion phase and that could be regulated by EUV photoevaporation. By considering the conventional nuclear burning and microscopic diffusion along the MS, we can reproduce the Spite plateau for stars with initial mass m(0) = 0.62-0.80 M-circle dot, and the Li declining branch for lower mass dwarfs, e.g. m(0) = 0.57-0.60 M-circle dot, for a wide range of metallicities (Z = 0.00001 to Z = 0.0005), starting from an initial Li abundance A(Li) = 2.72. This environmental Li evolution model also offers the possibility to interpret the decrease of Li abundance in extremely metal-poor stars, the Li disparities in spectroscopic binaries and the low Li abundance in planet hosting stars.
2015
452
3
3256
3265
https://doi.org/10.1093/mnras/stv1384
https://arxiv.org/abs/1506.05993
Fu, Xiaoting; Bressan, Alessandro; Molaro, Paolo; Marigo, Paola
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/14810
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