Can active late-type stars contribute to the Galactic lithium abundance?

Abstract

Abstract Lithium abundances in our Galaxy and especially 6Li abundances provide important constraints on our understanding of Big Bang Nucleosynthesis (BBNS), stellar evolution and the creation of light elements by cosmic rays in the ISM. 6Li has been detected in energetic solar events, one chromospherically active binary and several dwarf halo stars. Continuing our work on active late-type stars with high lithium abundances, we expand our study to consider if the flare origin of lithium created by spallation can contribute significantly to the Galactic abundance of lithium. We previously derived 6 Li 7 Li = 0.030 ± 0.010 for active K dwarf GJ 117 using VLT UVES observations. We find 6 Li 7 Li ratios of 0.02 and 0.10 for two other stars in our sample, GJ 182 and EUVE J1145–55.3A, respectively. Considering that these later type, active stars have significant flare rates and stellar winds, we have estimated the contribution of these stars to the Galactic lithium abundance. Given that K and M stars comprise over 84% of our Galaxy and that many of these can have significant stellar winds, we conclude that spallation in stellar flares can contribute 1% and up to 5% of the Galactic lithium abundance.