Detection of a high-velocity sodium feature on the ultra-hot Jupiter WASP-121 b J. V. Seidel, F. Borsa, L. Pino, D. Ehrenreich, M. Stangret, M. R. Zapatero Osorio, E. Palle, Y. Alibert, R. Allart, V. Bourrier et al. (12 more) A&A, 673 (2023) A125 Published online: 17 May 2023 DOI: 10.1051/0004-6361/202245800