Water content trends in K2-138 and other low-mass multi-planetary systems L. Acuña, T. A. Lopez, T. Morel, M. Deleuil, O. Mousis, A. Aguichine, E. Marcq and A. Santerne A&A, 660 (2022) A102 Published online: 25 April 2022 DOI: 10.1051/0004-6361/202142374