Astronomical Infrared Spectrum of Planetary Nebula Lin49 and Tc1 Identified by Ionized Polycyclic-Pure-Carbon C23 and C60

TL;DR

This study identifies polycyclic-pure-carbon C23 molecules in planetary nebulae using quantum-chemical calculations, explaining their infrared spectra and supporting the presence of ionized fullerenes like C60.

Contribution

It introduces a novel identification of C23 molecules in nebulae and demonstrates their spectral match with observed infrared data, expanding understanding of cosmic carbon molecules.

Findings

Ionized C23 molecules reproduce 28 observed infrared peaks.

Neutral C60 matches 5 observed spectral bands.

Ionized C60 shows good agreement with 10 spectral features.

Abstract

Astronomical dust molecule of carbon-rich nebula-Lin49 and nebula-Tc1 could be identified to be polycyclic-pure-carbon C23 by the quantum-chemical calculation. Two driving forces were assumed. One is high speed proton attack on coronene-C24H12, which created void-induced C23H12. Another is high energy photon irradiation, which brought deep photo-ionization and finally caused dehydrogenation to be C23. Infrared spectrum calculation show that a set of ionized C23 (neutral, mono, and di-cation) could reproduce observed many peaks of 28 bands at wavelength from 6 to 38 micrometer. Previously predicted neutral fullerene-C60 could partially reproduce observed spectrum by 5 bands. Also, we tried calculation on ionized-C60, which show fairly good coincidence with observed 10 bands