The intrinsic high metallicity of cSNRs

Here we present semi-analytical solutions of the hydrodynamics of compact supernova remnants (cSNRs) and their chemical evolution. Two models of $15 M_{\odot}$ and $25 M_{\odot}$ supernova explosions evolving in a high density medium ($n_0 \sim 10^7 cm^{-3}$) are throughly discussed.