9 Sagittarii: uncovering an O-type spectroscopic binary with an 8.6 year periodG. Rauw, H. Sana, M. Spano, E. Gosset, L. Mahy, M. De Becker and P. EenensA&A, 542 (2012) A95DOI: https://doi.org/10.1051/0004-6361/201219254