7450 20250128075305.0 10.1017/S174392132200206X DOI SCART-2025-0081 Fabry, M. Constraining the dynamical mass of the massive binary 9 Sagittarii 2024 Especially in the upper Hertzsprung-Russell diagram, where stellar physics is least understood, obtaining model independent masses is of great value. Spectroscopic binaries that are also resolved astrometrically are an excellent alternative to eclipsing double-lined spectroscopic binaries where dynamical masses can be measured. 9 Sgr is such a massive binary. However, its characterization is troubled by conflicting conclusions from the spectroscopic analysis on the one hand and the interferometric one on the other hand. In this work, we attempt to resolve this tension by applying a novel approach to spectral disentangling of the spectroscopic data to constrain better the mass of 9 Sgr. NO Hawcroft, C. Frost, A. J. Mahy, L. Marchant, P. Le Bouquin, J.-B. Sana, H. Massive Stars Near and Far, Edited by J. Mackey, J.S. Vink and N. St-Louis. Proceedings of the International Astronomical Union, held 8-13 May 2022 in Ballyconnell, Ireland. Cambridge University Press, 2024 361 2024 305-306 laurent.mahy@ksb-orb.be 283570 http://publi2-as.oma.be/record/7450/files/Fabry_IAU361.pdf 19527 http://publi2-as.oma.be/record/7450/files/Fabry_IAU361.gif?subformat=icon icon 23477 http://publi2-as.oma.be/record/7450/files/Fabry_IAU361.jpg?subformat=icon-180 icon-180 published in NONREF