Discovery of a highly magnetic He-sdO star from a double-degenerate binary merger M. Dorsch, N. Reindl, I. Pelisoli, U. Heber, S. Geier, A. G. Istrate and S. Justham A&A, 658 (2022) L9 Published online: 08 February 2022 DOI: 10.1051/0004-6361/202142880