Measurement of the Oxidation state of Fe in the ISM using X-ray Absorption Spectroscopy

TL;DR

This study uses X-ray absorption spectroscopy to determine the oxidation state of iron in the interstellar medium, providing insights into the chemical processes that influenced the early Solar System's building blocks.

Contribution

It introduces a novel application of synchrotron X-ray absorption spectra to measure Fe oxidation states in the ISM, linking interstellar chemistry to Solar System formation.

Findings

Fe in the ISM is in a specific oxidation state constrained by X-ray spectra.

Primordial Solar System materials show diverse oxidation states.

Evidence suggests nebular oxidation of cometary material before incorporation.

Abstract

The oxidation state of iron in the interstellar medium (ISM) can provide constraints on the processes that operated on material in the protosolar disk. We used synchrotron-based X-ray absorption spectra of several mineral standards and two kinds of primitive extraterrestrial materials to constrain the oxidation state and mineralogy of the host-phase of ISM Fe as measured by X-ray observations of Fe-L ISM absorption from the {\em Chandra X-ray Observatory}. Given the initial oxidation state of the building blocks of the Solar System, we explore nebular and parent-body processes that eventually led to the remarkable diversity of oxidation states of primitive Solar System materials. Oxidation of cometary material appears to have taken place in the nebula, before incorporation into cometary nuclei, although the mechanism is unknown.