Gravitational fragmentation caught in the act: the filamentary Musca molecular cloud J. Kainulainen, A. Hacar, J. Alves, H. Beuther, H. Bouy and M. Tafalla A&A, 586 (2016) A27 Published online: 22 January 2016 DOI: 10.1051/0004-6361/201526017