Flare Production of ${}^6$Li in Population~II Stars

Abstract

Motivated by the recent report of a ${}^6$Li detection in the atmosphere of HD~84937, we couple stellar evolution calculations with light isotope production via stellar flares. We find that as a consequence of their small convective envelope mass near the turn-off point, low-metallicity dwarfs and subgiants may possess observable amounts of ${}^6$Li arising from such flare activity. We point out an observational test which could discriminate between flare produced ${}^6$Li and protostellar ${}^6$Li. In the $T_{\mathrm{eff}}$ range $6000-6600$~K, the ${}^7$Li/${}^6$Li ratio on the subgiant branch should increase as a function of $T_{\mathrm{eff}}$ if flare production is important, whereas the same ratio should be constant if a protostellar origin is the source of the observed lithium. The absence of a flare produced variation in the ${}^7$Li/${}^6$Li ratio would allow for a more reliable inference of the -- cosmologically important -- atmospheric depletion mechanisms in stars.

14 pages, 6 figs available on request, Tex, CITA/94/19

Cited by in corpus (11)

• Big-bang Nucleosynthesis Enters the Precision Era
• The Spite Lithium Plateau: Ultra-Thin but Post-Primordial
• Production and evolution of Li, Be and B isotopes in the Galaxy
• The Lithium Content of the Galactic Halo Stars
• Stellar coronal astronomy - a review
• An Ultra-High-Resolution Survey of the Interstellar ^7Li-to-^6Li Isotope Ratio in the Solar Neighborhood
• Is 6-Li in metal-poor halo stars produced in situ by solar-like flares?
• A low upper-limit on the lithium isotope ratio in HD140283
• Cosmic-Ray Lithium Production at the Nova Eruption Followed by a Type Ia Supernova
• The Deuteron Confronts Big Bang Nucleosynthesis
• 6^Li in the atmosphere of GJ 117