Low and intermediate mass star yields.II: The evolution of nitrogen   abundances
  We analyze the impact on the Galactic nitrogen abundances of using a new set of low and intermediate mass star yields. These yields have a significant yield of primary nitrogen from intermediate mass stars. We use these yields as an input to a Galactic Chemical Evolution model and study the nitrogen abundances in the halo and in the disc, and compare them with models obtained using other yield sets and with a large amount of observational data. We find that, using these new yields, our model adequately reproduce the observed trends. In particular, these yields solve the historical problem of the evolution of nitrogen, giving the right level of relative abundance N/O by the production of a primary component in intermediate mass stars. Moreover, using different evolutionary rates in each radial region of the Galaxy, we may explain the observed N dispersion. 
Marta Gavilan, Mercedes Molla & James F. Buell