Tracing the contraction of the pre-stellar core L1544 with HC17O+ J = 1–0 emission J. Ferrer Asensio, S. Spezzano, P. Caselli, F. O. Alves, O. Sipilä, E. Redaelli, L. Bizzocchi, F. Lique and A. Mullins A&A, 667 (2022) A119 Published online: 17 November 2022 DOI: 10.1051/0004-6361/202243927