The ALMA-QUARKS survey: Extensive detection of acetamide in multiple high-mass star-forming regions

¹ School of Chemistry and Chemical Engineering, Chongqing University, Daxuecheng South Rd. 55, Chongqing 401331, PR China
² Chongqing Key Laboratory of Chemical Theory and Mechanism, Chongqing University, Daxuecheng South Rd. 55, Chongqing 401331, PR China
³ Shanghai Astronomical Observatory, Chinese Academy of Sciences, Nandan Rd. 80, Shanghai 200030, PR China
⁴ Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, Nandan Rd. 80, Shanghai 200030, PR China
⁵ LUX, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, 75014 Paris, France
⁶ Department of Astronomy, Peking University, 5 Yiheyuan Road, Haidian District, Beijing 100871, PR China
⁷ Kavli Institute for Astronomy and Astrophysics, Peking University, 5 Yiheyuan Road, Haidian District, Beijing 100871, PR China
⁸ Leiden Observatory, Leiden University, PO Box 9513, 2300RA Leiden, The Netherlands

^★ Corresponding authors: xuefang_xu@cqu.edu.cn; qian.gou@cqu.edu.cn; liutie@shao.ac.cn

Received: 24 June 2025
Accepted: 18 August 2025

Abstract

Acetamide (CH₃CONH₂), a key interstellar amide and a methyl derivative of formamide (NH₂CHO), has rarely been detected, limiting insights into its prebiotic relevance. We present the first systematic survey of acetamide toward 52 hot molecular cores using ALMA Band 6 data. We have detected acetamide in ten cores, markedly expanding the inventory of known emitters. The derived column densities of acetamide range from (2.5 ± 0.9) × 10¹⁴ to (1.5 ± 0.6) × 10¹⁶ cm⁻², compared to formamide’s (1.1 ± 0.1) × 10¹⁵ to (6.9 ± 0.4) × 10¹⁶ cm⁻². The nearly constant abundance ratios (~3–9) and strong abundance correlation between the two amides across sources suggest a chemically linked formation pathway, likely on grain surfaces. The presence of peptide-like molecules in these regions implies that complex organic species can survive star formation processes, offering a potential pathway toward prebiotic chemistry. These findings constrain the dominant grain-surface formation routes of acetamide, confirm its broader prevalence in high-mass star-forming regions, and underscore the importance of targeted amide surveys in tracing the chemical evolution toward prebiotic complexity.