Expert in: Stellar rotation
- Fundamental astronomy
- Fundamental aspects of astrophysics
- Spectroscopy and spectrophotometry
- Time series analysis, time variability
- Corotating streams
- Circumstellar shells
- Stellar rotation
- Mass loss and stellar winds
- Emission-line stars (Of, Be, LBV, Wolf-Rayet stars)
My research is mainly on the wind from the most massive stars. In view of their great luminosity - reaching one million times that of the Sun - these stars lose a large proportion of their mass over their lifetimes. This stellar wind is not symmetrical or homogenous. Not only does it contain small-scale inhomogeneities relating to turbulence, but in some cases also large-scale structures. These structures are particularly intriguing, since they are created by an as-yet unidentified mechanism occurring at the surface of the star.
The possible mechanisms include magnetic fields and pulses, two important physical processes in the evolution of massive stars, but about which we still have very little information.
The consequences of these large-scale structures for observable data (spectrum, photometry, polarization rate) can also help us to determine a fundamental parameter of these stars: their rotation velocity. This important detail is usually impossible to measure for the massive stars I am studying, since their surface is completely concealed behind the very dense wind. Because the large-scale structures are attached to the surface, identifying a period in the star's spectral or luminous variations lets us deduce the rotation velocity.