Are Lithium-Rich Red Giants the Source of Most of the Galactic Lithium?
Abstract
Mass loss from the 1%-3% of the carbon and S stars that are super-Li-rich (Li/H can be 3 times 10^{-6} or 1500 times the ISM Li/H) is the most likely source of much of the Galactic Li. In these stars ^7Li is produced via ^3He(alpha,gamma)^7Be during hot-bottom burning in the AGB phase followed by convection of the ^7Be to the surface where ^7Be(e,nu)^7Li occurs during the 10^4 years that they are Li-rich. Mass loss of 10^{-6} to 10^{-7} solar mass/yr can produce Li/H = 1 times 10^{-9}. This result depends on accurate knowledge of 1) Li/H in red giant stars; 2) the number density of Li-rich stars; 3) the mass loss rate while these stars are Li-rich; 4) the lifetime of the Li-rich phase. A summary of work in progress will be presented to determine 1; 2; 3; an age - Li/H relationship; a chromospheric activity - Li/H relationship; and if planetary nebulae results from progenitor AGB stars that are Li-rich..
- Publication:
-
19th Texas Symposium on Relativistic Astrophysics and Cosmology
- Pub Date:
- December 1998
- Bibcode:
- 1998tx19.confE.210L