AN ALTERNATIVE EXPLANATION OF THE EVOLUTION OF ELEMENT ABUNDANCE RATIOS DURING THE HISTORY OF THE GALAXY

It is well established that stellar element abundances show a variation of some ratios, such as oxygen to iron and calcium to iron, with the overall metallicity of the star. This has been ascribed to a time-delay, effect due to the different mean lifetimes of the stars and binaries that give rise to Type II and type I supernovae. We propose here that this identification may be premature. and that the observations could equally well be explained by a 'pseudo-secondary' behaviour in the nucleosynthesis of iron.