A mechanism for the formation of oxygen and iron bimodal radial distribution in the disc of our Galaxy

Abstract

Recently, it has been proposed that there are two type Ia supernova progenitors: short-lived and long-lived. On the basis of this idea, we develop a theory of a unified mechanism for the formation of the bimodal radial distribution of iron and oxygen in the Galactic disc. The underlying cause for the formation of the fine structure of the radial abundance pattern is the influence of the spiral arms, specifically the combined effect of the corotation resonance and turbulent diffusion. From our modelling, we conclude that in order to explain the bimodal radial distributions simultaneously for oxygen and iron and to obtain approximately equal total iron output from different types of supernovae, the mean ejected iron mass per supernova event should be the same as quoted in the literature if the maximum mass of stars, which eject heavy elements, is 50 M⊙. For the upper mass limit of 70 M⊙, the production of iron by a type II supernova explosion should increase by about 1.5 times. © 2009 The Authors. Journal compilation © 2009 RAS.