Galactic chemical evolution ( GCE ) models which include sodium from type II supernovae ( SNe ) alone underestimate the abundance of sodium in the interstellar medium by a factor of two to three over about 3 \mathrm { dex } in metallicity and predict a flat behaviour in the evolution of [ \mathrm { Na } / \mathrm { Fe } ] at super-solar metallicities .
Conversely , recent observations of stars with [ \mathrm { Fe } / \mathrm { H } ] \sim + 0.4 suggest that [ \mathrm { Na } / \mathrm { Fe } ] increases at high metallicity .
We have combined stellar evolution models of asymptotic giant branch ( AGB ) and Wolf-Rayet ( WR ) stars with the latest SN yields in an attempt to resolve these problems …and have created many more .