A Cyanopolyyne-rich But COM-poor Massive Protostar: The First Hot Carbon Chain Chemistry Source G28.28-0.36

[astro-ph.GA] We present molecular emission line data from the massive young stellar object (MYSO) G28.28-0.36 (G28.28) obtained with the Atacama Large Millimeter/submillimeter Array Band 3. Cyanopolyynes (HC₃N and HC₅N) and three complex organic molecules (COMs; CH₃OH, CH₃CN, and CH₃CHO) are detected from the MYSO G28.28.

In addition, strong emission regions of cyanopolyynes are identified between G28.28 and a nearby ultracompact H II region.

The HC₅N emission is coincident with the dust continuum peak, where an excitation temperature of 100 K is derived from CH₃CN.

These results suggest that the Hot Carbon Chain Chemistry (HCCC) mechanism produces cyanopolyynes in the hot region around G28.28. We find that G28.28 exhibits a unique chemical feature: cyanopolyynes are abundant, but COMs are deficient, unlike the other MYSOs studied previously.

These results imply that G28.28 is a counterpart of the Warm Carbon Chain Chemistry (WCCC) low-mass source L1527. G28.28 is the first HCCC source identified so far.

Kotomi Taniguchi, Masao Saito, Prasanta Gorai, Olli Sipilä, Kazuhito Dobashi, Paola Caselli, Tirupati Kumara Sridharan, Tomomi Shimoikura, Jonathan C. Tan

Comments: Accepted by The Astrophysical Journal, 18 pages, 10 figures, 6 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2609.30654 [astro-ph.GA](or arXiv:2609.30654v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2609.30654
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Submission history
From: Kotomi Taniguchi Dr.
[v1] Fri, 25 Sep 2026 00:46:07 UTC (6,603 KB)
https://arxiv.org/abs/2609.30654

Astrobiology, Astrochemistry,