# Oxygen-rich droplets and the enrichment of the ISM

## TL;DR

This paper proposes that metal-rich droplets formed from supernova ejecta explain the observed abundance discrepancies in HII regions, linking ISM enrichment processes with emission line observations.

## Contribution

It introduces a scenario where supernova-enriched droplets cause ORL-CEL abundance discrepancies, connecting stellar feedback with nebular emission line diagnostics.

## Key findings

- Metal-rich droplets form after supernova explosions.
- These droplets cause enhanced recombination lines of metals.
- The scenario explains the ORL-CEL abundance discrepancy.

## Abstract

We argue that the discrepancies observed in HII regions between abundances derived from optical recombination lines (ORLs) and collisionally excited lines (CELs) might well be the signature of a scenario of the enrichment of the interstellar medium (ISM) proposed by Tenorio-Tagle (1996). In this scenario, the fresh oxygen released during massive supernova explosions is confined within the hot superbubbles as long as supernovae continue to explode. Only after the last massive supernova explosion, the metal-rich gas starts cooling down and falls on the galaxy within metal-rich droplets. Full mixing of these metal-rich droplets and the ISM occurs during photoionization by the next generations of massive stars. During this process, the metal-rich droplets give rise to strong recombination lines of the metals, leading to the observed ORL-CEL discrepancy. (The full version of this work is submitted to Astronomy and Astrophysics.)