Our team has performed numerical simulations on DIaL-2.5 and DIaL-3 of convection in the core of a star of 5 solar masses. We have studied the excitation of internal gravity waves excited by the convective motions. The study of these waves in a stellar astrophysics context is very topical as recent observational studies suggest that the photometric variability detected at the surface of many stars in this mass range are due to waves excited by core convection and propagating towards the surface (e.g. Bowman D. M. et al. 2019, A&A, 621, 135). This interpretation relies on the comparison between observations and previous numerical simulations (e.g. Rogers T. M. et al. 2013, ApJ, 772). If this interpretation were to be confirmed, these waves would provide valuable constraints on the size of a convective core and on the process of overshooting that is still poorly described in stellar evolution models. But our state-of-the-art numerical simulations performed with the fully compressible time implicit code MUSIC show that these waves are strongly damped due to radiative damping as they approach the stellar surface. These results suggest that internal waves excited by core convection will not be able to reach the surface. The interpretation of the signal observed at the surface of massive stars thus remains an open question. 

 
Publications resulting from this work:  Baraffe et al. 2023; Le Saux et al. 2023.  

Left: Visualisation of the radial velocity within a 5 solar mass star illustrating the convective motions in the central core and the waves excited at the core boundary and propagating outwards. Right: Power spectrum of waves as function of frequency and stellar radius illustrating the strong damping of low frequency waves as they reach the stellar surface.