Lithium in the closest satellite of our Milky Way

G. Cescutti, P. Molaro, X. Fu

Published 2020-04-14Version 1

Recently, we studied the chemical evolution of lithium in the thin disc of the Milky Way. We found that the best agreement with the observed Li abundances in the thin disc is obtained considering novae as the main source of lithium. We assumed a delay time of ~1 Gyr for nova production and an effective 7Li yield of 1.8($\pm$0.6)x10$^{-5}$ Msun over the whole nova lifetime. The possibility to check our detailed assumptions on lithium production on other stellar systems, such as the satellites of our Milky Way, is seriously hampered by their distance from us. In these systems dwarf stars (where the original lithium can be measured) are too faint to detect lithium lines. However, thanks to the Gaia mission, it was recently possible to disentangle the stars of a disrupted dwarf galaxy in the Galactic halo (called Enceladus or Galactic sausage). Adopting a chemical evolution model tuned to match the metallicity distribution function of Enceladus stars, we present our predictions for the lithium abundance of the stars of this disrupted galaxy.