A lighter core for Phobos? Xi Guo, Jianguo Yan, Tom Andert, Xuan Yang, Martin Pätzold, Matthias Hahn, Mao Ye, Shanhong Liu, Fei Li and Jean-Pierre Barriot A&A, 651 (2021) A110 Published online: 27 July 2021 DOI: 10.1051/0004-6361/202038844