A Cyanopolyyne-rich but Complex-organic-molecule-poor Massive Protostar: The First Hot Carbon-chain Chemistry Source G28.28-0.36
Abstract 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 (HC 3 N and HC 5 N) and three complex organic molecules (COMs; CH 3 OH, CH 3 CN, and CH 3 CHO) 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 HC 5 N emission is coincident with the dust continuum peak, where an excitation temperature of 100 K is derived from CH 3 CN. 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.
Authors
- Prasanta Gorai (ORCID: https://orcid.org/0000-0003-1602-6849)
- Tomomi Shimoikura (ORCID: https://orcid.org/0000-0002-1054-3004)
- Kazuhito Dobashi (ORCID: https://orcid.org/0000-0001-8058-8577)
- O. Sipilä (ORCID: https://orcid.org/0000-0002-9148-1625)
- T. K. Sridharan (ORCID: https://orcid.org/0000-0001-5921-5784)
- Kotomi Taniguchi (ORCID: https://orcid.org/0000-0003-4402-6475)
- Masao Saito (ORCID: https://orcid.org/0000-0003-0769-8627)
- Paola Caselli (ORCID: https://orcid.org/0000-0003-1481-7911)
- Jonathan C. Tan (ORCID: https://orcid.org/0000-0002-3389-9142)
Institutions
- Otsuma Women's University (JP)
- Tokyo Gakugei University (JP)
- University of Oslo (NO)
- National Institutes of Natural Sciences (JP)
- The Graduate University for Advanced Studies, SOKENDAI (JP)
- Heidelberg University (DE)
- National Radio Astronomy Observatory (US)
- Max Planck Institute for Extraterrestrial Physics (DE)
- University of Virginia (US)
- Chalmers University of Technology (SE)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2026-11-02
- DOI
- https://doi.org/10.3847/1538-4357/aeacdb
- Primary Topic
- Astrophysics and Star Formation Studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- National Radio Astronomy Observatory
- Korea Astronomy and Space Science Institute
- Max-Planck-Gesellschaft
- National Astronomical Observatory of Japan
- National Science and Technology Council
- Japan Society for the Promotion of Science
- National Institutes of Natural Sciences