Discovery of technetium- and niobium-rich S stars: The case for bitrinsic stars S. Shetye, S. Van Eck, S. Goriely, L. Siess, A. Jorissen, A. Escorza and H. Van Winckel A&A, 635 (2020) L6 Published online: 04 March 2020 DOI: 10.1051/0004-6361/202037481