Massive stars asteroseismology in the TESS era: pulsations and binarity in young Galactic clusters
Abstract
Massive stars are the progenitors of neutron stars, black holes and gravitational wave sources, yet their internal structure and evolution remain poorly constrained. A major complication for an (asteroseismic) analysis of massive stars is binarity. Numerous surveys demonstrated that the majority of massive stars are found in multiple systems making interaction phases of mass transfer highly likely. The variety of potential post-interaction products means single-star evolution models are not applicable anymore. Moreover, the amount of internal mixing influences a massive star's main-sequence lifetime and its helium core mass, which in turns dictates the type of compact object remnant. Fortunately, pulsations mitigate these uncertainties and allow asteroseismology to calibrate the internal structure and evolution of massive stars, especially if coupled with binary modelling. To achieve this, we need stringent observational constraints on pulsating massive binaries. In this talk, I will present the photometric analysis of 74 early B-type stars in four young Galactic clusters, performed using high-precision time series photometry provided by TESS. I will show how both binarity and pulsations are nearly ubiquitous, since the overall binary fraction of the clusters is about 80%, and nearly all stars exhibit pulsational variability. By constructing an asteroseismic Hertzsprung–Russell diagram, I will explore the impact of binarity on pulsation properties and discuss particularly interesting objects. These findings emphasise that neither binarity nor pulsations can be ignored when studying massive star evolution. Finally, we showcase the potential of using TESS in optimising target lists for future PLATO proposals of massive stars in clusters.