Research
My research focuses on massive stars, stars with masses higher than 8 times the mass of our Sun. They are about one hundred thousands times brighter than our Sun, and their stellar winds are up to ten billion times stronger than our solar wind. They are the progenitors of the most powerful explosions in the Universe, leaving behind black hole or neutron star remnants as they die when exploding as supernovae. With their high luminosities, strong stellar winds and spectacular explosions, they heat and enrich their surrounding gas clouds where new generations of stars and planets form, and drive the chemical evolution of galaxies.
We now know that a vast majority of these objects are found in multiple systems, meaning that they interact with their companions during their lifetime. These interactions affect the way that the massive stars evolve. A part of my research is devoted to analyse these interactions and how they influence the stellar evolution. To do so, I use multi-wavelength spectroscopy, photometry, and interferometry. The data are collected with the world's largest telescopes and satellites. With these facilities, I am able to infer the observational properties of massive stars and binaries in the Local Group. I developed and utilise state-of-the-art model atmospheres and spectral disentangling algorithms to derive robust constraints on the progenitors of compact objects such as Wolf-Rayet stars, OB-type stars, or stripped stars, with the goal of advancing our understanding of the evolution of massive stars and binaries and the production of gravitational-wave sources.
With the detections of gravitational waves by the Advanced-LIGO detectors, a new decisive phase for the study of massive stars has been opened, providing fi rst observational evidence for the existence and merging of binary black hole systems. This discovery raised a lot of questions about the evolution of massive stars, especially about their winds, the binary interactions and their internal structure. To answer these different questions, I am working with Profs. Hugues Sana, Jon Sundqvist, Alex de Koter and Leen Decin as part of the MAESTRO (MAssivE STaR Outflows) team. This team consists of academics, postdocs and PhD students from within the KU Leuven. I notably obtained 42 orbits with the Hubble Space Telescope to obtain UV specctra of a massive star sample in the LMC and SMC, to characterise their wind properties.
Finally, another of my research interests is to understand what the Luminous Blue Variable (or LBV) stars are. These objects are a small and enigmatic group of hot and massive stars. They show extreme variability visible photometrically and spectroscopically that goes from microvariability to giant eruptions such as observed in the XVIIth century for P Cygni or in the XIXth century for Eta carinae. Some of them are also surrounded by nebulae, witnesses of their mass ejection history. According to the current evolutionary models of massive stars (and depending on their initial mass), massive stars evolve into Wolf-Rayet stars by going through this LBV phase. I traced back the moment of these objects have ejected their surrounding material but the characterisation of their history is inherent to the very nature of the central objects. Are they multiple systems, mergers, single stars? A lot of interesting discoveries need to be done in the coming years on these mysterious stellar objects.
Publications
A full list of my publications can be obtained via the NASA/ADS link below.
Stay abroad
As an astronomer and a researcher, I must travel the world for observing runs, conferences and meetings or research experiences and collaborations. Here is a summary of my different experiences: