The stellar origin of Li

Do AGB stars contribute a substantial fraction of the local Galactic lithium abundance?

¹ International School for Advanced Studies, SISSA/ISAS, Via Beirut 2-4, 34014 Trieste, Italy
² Dipartimento di Astronomia, Università di Trieste, Via G.B. Tiepolo 11, 34131 Trieste, Italy
³ Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy

Corresponding author: D. Romano, romano@sissa.it

Received: 22 December 2000
Accepted: 25 May 2001

Abstract

We adopt up-to-date ⁷Li yields from asymptotic giant branch stars in order to study the temporal evolution of ⁷Li in the solar neighbourhood in the context of a revised version of the two-infall model for the chemical evolution of our galaxy. We consider several lithium stellar sources besides the asymptotic giant branch stars such as type II supernovae, novae, low-mass giants as well as Galactic cosmic rays and low-mass X-ray binaries. We conclude that asymptotic giant branch stars cannot be considered as important ⁷Li producers as believed so far and that the contribution of low-mass giants and novae is necessary to reproduce the steep rise of the ⁷Li abundance in disk stars as well as the meteoritic ⁷Li abundance. Lithium production in low-mass X-ray binaries hardly affects the temporal evolution of ⁷Li in the solar neighbourhood.