Southern Massive Stars at High Angular Resolution

14th Hellenic Astronomy Conference
8 July 2019, Volos, Greece

One of the most striking features of massive stars is their high degree of multiplicity, and their evolution is dominated by binary interactions. As such, it is important to characterise the properties of the companions to these stars. Typically, companions are found either through spectroscopy (close companions) or direct
imaging (distant companions), leaving a large range of medium separations mostly unexplored. The ‘Southern Massive Stars at High Angular Resolution’ project observed all nearby Southern massive stars with two interferometric instruments on ESO’s VLT, closing the gap between spectroscopy and direct imaging. In this talk I will give a short overview of the project and present the most important results in terms of number of companions, and the distributions of separations and mass ratios.

27 March 2019, Athens, Greece

In this talk I will review my recent work on several aspects of massive stars. As it has become increasingly clear that multiplicity is a dominating factor in massive star evolution, I will discuss the properties of three very massive binary systems: WR21a, potentially the most massive binary in the Galaxy; R144, potentially the most massive binary in the LMC; and VFTS 352, the most massive over-contact binary known to date. Shifting to the very late stages of evolution, I will then present the properties of the illusive oxygen Wolf-Rayet stars, the rarest stage of massive star evolution, and show that these stars are on the verge of exploding as supernovae. Finally, I will talk about the properties of massive stars in low-metallicity Local Group galaxies, and how these can be used to help us understand the early Universe.