The primordial binary population - I. A near-infrared adaptive optics search for close visual companions to A star members of Scorpius OB2M. B. N. Kouwenhoven, A. G. A. Brown, H. Zinnecker, L. Kaper and S. F. Portegies ZwartA&A, 430 1 (2005) 137-154DOI: https://doi.org/10.1051/0004-6361:20048124