Constraints on the multiplicity of the most massive stars known: R136 a1, a2, a3, and c T. Shenar, H. Sana, P. A. Crowther, K. A. Bostroem, L. Mahy, F. Najarro, L. Oskinova and A. A. C. Sander A&A, 679 (2023) A36 Published online: 01 November 2023 DOI: 10.1051/0004-6361/202346930