Long baseline interferometry applied to the study of massive stars: current observations and prospects for VSI

Recent advances in the development of interferometric instruments coupled to long baseline facilities such as the VLTI allow us to observe astronomical targets at the milli-arcsecond scale. In the context of the study of massive stars, this new tool is likely to provide crucial information on the multiplicity of massive stars, and on interactions in colliding-wind binaries. In this context, our group is leading observation campaigns with the VLTI aiming at investigating massive multiple systems. I will briefly present these campaigns and discuss prospects for observations with next generation instruments such as the VLTI-Spectro-Imager (VSI).