High-contrast imaging of massive stars: the example of QZ Car

The formation of massive stars remains one of the most intriguing questions in astrophysics today. Several formation theories, that could potentially be tested by the multiplicity properties of their outcome, have been proposed. There are, however, observational challenges preventing us from discriminating between the different formation scenarios: massive stars are rare and found at relative large distances from us, they form on short timescales and evolve in multiple stellar systems within the gas-rich environment from which they are born. Taking advantage of the extreme-adaptive optics capabilities of VLT/SPHERE, we observed more than 70 galactic O stars, about half in the Carina nebula and another half in the galactic field or clusters and associations, aiming at characterizing their multiplicity properties. SPHERE offers unprecedented imaging contrasts which allows us to detect even the faintest companions around massive stars. Here, we illustrate its capabilities by focussing on the high-order multiple system QZ Car.