Detections of interstellar aromatic nitriles 2-cyanopyrene and 4-cyanopyrene in TMC-1
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s41550-024-02410-9.pdf
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Published version
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Checksum (MD5)
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Author(s)
Wenzel, Gabi
Speak, Thomas H
Changala, P Bryan
Willis, Reace HJ
Burkhardt, Andrew M
Zhang, Shuo
Bergin, Edwin A
Byrne, Alex N
Charnley, Steven B
Fried, Zachary TP
Date Issued
November 5, 2024
Journal
Nature Astronomy
Publisher
Springer Science and Business Media LLC
Citation
Wenzel, G., Speak, T.H., Changala, P.B. et al. Detections of interstellar aromatic nitriles 2-cyanopyrene and 4-cyanopyrene in TMC-1. Nat Astron 9, 262–270 (2025).
Version
Final published version
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread compounds in the universe, accounting for up to ~25% of all interstellar carbon. Since most unsubstituted PAHs do not possess permanent electric dipole moments, they are invisible to radio astronomy. Constraining their abundances relies on the detection of polar chemical proxies, such as aromatic nitriles. Here we report the detection of 2-cyanopyrene and 4-cyanopyrene, isomers of the recently detected 1-cyanopyrene. We find that these isomers are present in an abundance ratio of ~2:1:2, which mirrors the number of equivalent sites available for CN addition. We conclude that there is evidence that the cyanopyrene isomers formed by direct CN addition to pyrene under kinetic control in hydrogen-rich gas at 10 K and discuss constraints on the H/CN ratio for PAHs in the Taurus molecular cloud (TMC-1). Our detections of the cyanopyrene isomers suggest that small PAHs like pyrene must be either formed in or transported to the cold interstellar medium, challenging assumptions about the origin and fate of PAHs in space.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1038/s41550-024-02410-9
