A Mechanism for the Oxygen and Iron Bimodal Radial Distribution Formation in the Disc of our Galaxy

TL;DR

This paper proposes a unified mechanism involving spiral arm dynamics and supernova progenitor types to explain the bimodal radial distribution of oxygen and iron in the Milky Way's disc.

Contribution

It introduces a new theory linking spiral arm effects and supernova progenitor diversity to the galaxy's chemical abundance patterns.

Findings

Bimodal distributions explained by spiral arm influence and supernova types.

Iron and oxygen distributions can be modeled with consistent supernova yields.

The model constrains supernova iron yields based on stellar mass limits.

Abstract

Recently it has been proposed that there are two types of SN Ia progenitors -- short-lived and long-lived. On the basis of this idea, we develope 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 spiral arms, specifically, the combined effect of the corotation resonance and turbulent diffusion. From our modelling we conclude that 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 literature if maximum mass of stars, that eject heavy elements, is $50 M_{\odot}$. For the upper mass limit of $70 M_{\odot}$ the production of iron by a supernova II explosion should be increased by about 1.5 times.