Interstellar

Infrared Emission of Specific Polycyclic Aromatic Hydrocarbon Molecules: Cyanonaphthalenes

By Keith Cowing

Status Report

astro-ph.GA

March 12, 2024

Filed under astro-ph.GA, astrochemistry, cyanonaphthalenes, Interstellar, JWST, Polycyclic Aromatic Hydrocarbon, Spectroscopy, Taurus Molecular Cloud

Infrared Emission of Specific Polycyclic Aromatic Hydrocarbon Molecules: Cyanonaphthalenes — Left panel (a): Comparison of the IR emission spectra of 1-CNN of a natural line width of γ = 30 cm−1 (red line) for each vibrational transition with that of γ = 10 cm−1 (blue line). The molecule is illuminated by the MMP83 (U = 1) interstellar radiation field. Right panel (b): Same as (a) but for a comparison of γ = 30 cm−1 (red line) with γ = 50 cm−1 (blue line). – astro-ph.GA

The unidentified infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, 11.3 and 12.7 micron are ubiquitously seen in a wide variety of astrophysical regions and commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules.

However, the unambiguous identification of any individual, specific PAH molecules has proven elusive until very recently two isomers of cyanonapthalene, which consists of two fused benzene rings and substitutes a nitrile (-CN) group for a hydrogen atom, were discovered in the Taurus Molecular Cloud based on their rotational transitions at radio frequencies.

To facilitate the James Webb Space Telescope (JWST) to search for cyanonapthalenes in astrophysical regions, we model the vibrational excitation of cyanonapthalenes and calculate their infrared emission spectra in a number of representative astrophysical regions. The model emission spectra and intensities will allow JWST to quantitatively determine or place an upper limit on the abundance of cyanonapthalenes.

Kaijun Li, Aigen Li, Xuejuan Yang, Taotao Fang

Comments: 18 pages, 7 figures; accepted for publication in The Astrophysical Journal
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2403.05043 [astro-ph.GA] (or arXiv:2403.05043v1 [astro-ph.GA] for this version)
Submission history
From: Kaijun Li
[v1] Fri, 8 Mar 2024 04:37:57 UTC (97 KB)
https://arxiv.org/abs/2403.05043
Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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