The Serpens filament at the onset of slightly supercritical collapse Y. Gong, G. X. Li, R. Q. Mao, C. Henkel, K. M. Menten, M. Fang, M. Wang and J. X. Sun A&A, 620 (2018) A62 Published online: 28 November 2018 DOI: 10.1051/0004-6361/201833583