On Buckyonions as an Interstellar Grain Component

TL;DR

This paper investigates whether carbon buckyonions can be the carrier of the 2175 Angstrom interstellar extinction feature by modeling interstellar dust and comparing spectral predictions with observations.

Contribution

It demonstrates that dust models including buckyonions can accurately reproduce the interstellar extinction curve, supporting buckyonions as a potential carrier.

Findings

Buckyonions can closely match the 2175 Angstrom extinction feature.

Models with buckyonions fit observed interstellar extinction curves.

Infrared spectra predictions can help determine buckyonion abundance.

Abstract

The carrier of the 2175 Angstrom interstellar extinction feature remains unidentified since its first detection over 40 years ago. In recent years carbon buckyonions have been proposed as a carrier of this feature, based on the close similarity between the electronic transition spectra of buckyonions and the 2175 Angstrom interstellar feature. We examine this hypothesis by modeling the interstellar extinction with buckyonions as a dust component. It is found that dust models containing buckyonions (in addition to amorphous silicates, polycyclic aromatic hydrocarbon molecules, graphite) can closely reproduce the observed interstellar extinction curve. To further test this hypothesis, we call for experimental measurements and/or theoretical calculations of the infrared vibrational spectra of hydrogenated buckyonions. By comparing the infrared emission spectra predicted for buckyonions vibrationally excited by the interstellar radiation with the observed emission spectra of the diffuse interstellar medium, we will be able to derive (or place an upper limit on) the abundance of interstellar buckyonions.