Examples of the evolution of five SERIES I models with different initial masses in the log(ρ_c)−log(T_c) plane. Black dotted lines show approximate ignition curves taken from MESA. Black dashed lines indicate different pressure regimes while the hatched area shows the approximate region for e-captures on ²⁰Ne nuclei. The blue dashed line refers to the same stellar model as the one with the solid blue line; the only difference is that for the former, all carbon-participating reaction have been switched off prior to Urca cooling leading most likely to an ECSN. The density at which carbon reactions were turned off is marked by a black cross-mark.