JCMT detection of HCN emission from 3I/ATLAS at 2.1 au

Monthly Notices of the Royal Astronomical Society 2026 Open access

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Authors: I. M. Coulson, Yi-Jehng Kuan, Steven B. Charnley, Martin Cordiner, Yo-Ling Chuang, Y L. Lee, Min-Kai Lin, Stefanie N. Milam, Bannawit Pimpanuwat, Nathan X. Roth, Michał Żółtowski
DOI: 10.1093/mnras/stag063
Cited by: 13
References: 30

Abstract

ABSTRACT We report the detection of HCN($J=3-2$) rotational emission from comet 3I/ATLAS at a heliocentric distance of 2.13 au with the James Clerk Maxwell Telescope (JCMT). Observations were conducted between 2025 August 7 and 2025 September 14 (ut) using the $^{^{\prime }}\, \overline{U}\, ^{^{\prime }}\, \overline{u}$ heterodyne receiver and ACSIS (Auto Correlation Spectral Imaging System) spectroscopic backend. The HCN line was detected at $> 6 \sigma$ on 2025 September 14 (ut) and a production rate of $Q({\rm HCN})=(4.0\pm 1.7)\times 10^{25}$ s$^{-1}$ was derived by non-LTE radiative transfer modelling. Preliminary estimates of the HCN/H$_2$O and CN/HCN abundance ratios suggest values similar to Solar system comets.

Fields of Study & Subjects

Astro and Planetary Science Astrophysics and Star Formation Studies Stellar planetary and galactic studies

Publication details

Journal / source
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press (OUP)
Volume
546
Issue
2
Publication date
12 January 2026
Language
EN