Enhancement of Lithium in Red Clump Stars by Neutrino Magnetic Moments

Kanji Mori,Motohiko Kusakabe,Michael A Famiano,A Baha Balantekin,Toshitaka Kajino,W Liu,S Zeng,Y Wang,B Guo,X Tang

doi:10.1051/epjconf/202226011016

Abstract

A recent spectroscopic survey has shown that the lithium abundances in low-mass red-clump stars are higher than theoretical prediction. Motivated by their finding, we implemented effects of additional energy losses induced by neutrino magnetic moments on stellar evolution models. It is found that the lithium abundances in red giants increase because the finite magnetic moments of neutrinos enhance the efficiency of deep mixing and 7Be is conveyed from the hydrogen burning shell to the convective envelope. The results motivate further studies on the effects of non-standard energy losses on the surface compositions of low-mass red giants and red-clump stars.

Highlights

The lithium abundances in low-mass stars are long-standing problem in stellar modeling
Since stellar models predict that lithium in red giants is destroyed by the first dredge-up [3], the mechanism for the lithium enhancement in such giants is an open problem
A recent spectroscopic survey [5] has shown that almost all red-clump stars show the lithium abundances of A(Li) = 0.71 ± 0.39, which are higher than theoretical prediction

Summary

Introduction

The lithium abundances in low-mass stars are long-standing problem in stellar modeling. Giant stars with A(Li) = log N(Li)/N(H) + 12 > 1.5 are called lithium-rich giants [1, 2]. Since stellar models predict that lithium in red giants is destroyed by the first dredge-up [3], the mechanism for the lithium enhancement in such giants is an open problem. A recent spectroscopic survey [5] has shown that almost all red-clump stars show the lithium abundances of A(Li) = 0.71 ± 0.39, which are higher than theoretical prediction.

Results

Conclusion