The importance of { { } ^ { 14 } N } ( e ^ { - } , \gamma ) { { } ^ { 14 } C } ( \alpha, \gamma ) { { } ^ { 18 } O } ( NCO ) chain on the onset of the He-flash in degenerate physical conditions has been reevaluated .
We find that low-mass , metal-rich ( Z \geq 0.001 ) structures climbing the Red Giant Branch do never attain the physical conditions suitable for the onset of this chain , while at lower metallicities the energy contribution provided by NCO reaction is too low to affect the onset of the central He-flash .

At the same time , our evolutionary models suggest that for a Carbon-Oxygen White Dwarf of mass M _ { WD } = 0.6 M _ { \odot } accreting He-rich matter , directly or as a by-product of an overlying H-burning shell , at rates suitable for a dynamical He-flash , the NCO energy contribution is not able to keep hot enough the He-shell and in turn to avoid the occurrence of a strong electron degeneracy and the ensuing final explosion .