Emergence hour-by-hour of r-process features in the kilonova AT2017gfo Albert Sneppen, Darach Watson, Rasmus Damgaard, Kasper E. Heintz, Nicholas Vieira, Petri Väisänen and Antoine Mahoro A&A, 690 (2024) A398 Published online: 30 October 2024 DOI: 10.1051/0004-6361/202450317