Anomalously low-mass core-He-burning star in NGC 6819 as a post-common-envelope phase product Massimiliano Matteuzzi, David Hendriks, Robert G. Izzard, Andrea Miglio, Karsten Brogaard, Josefina Montalbán, Marco Tailo and Alessandro Mazzi A&A, 691 (2024) A17 Published online: 25 October 2024 DOI: 10.1051/0004-6361/202451092