Except for the lightest elements (H, He and Li), atoms are formed inside the stars, throughout its life, by nuclear reactions. But they need to escape. Among the most efficient escape mechanisms, there is the stellar wind and, in particular, that of the red supergiants. At the end of their life, these stars blow an intense and almost continuous stream of atoms of all kinds. But what is the origin of this stellar wind?
At the top of the Pic du Midi, southern France, the Bernard Lyot Telescope (TBL) studies Betelgeuse, the closest red supergiant to Earth. Recently, a new indirect imaging technique, based on the use of the polarization of the emitted light, has been developed. If, at first, only two-dimensional images were obtained, the technique has been improved and now produces three-dimensional images. The heated plasma inside the star can be seen rising towards the surface where it cools down. Heavier because colder, it should then fall back towards the interior of the star where it would be heated again in a convective cycle. But what we see on the 3D images of Betelgeuse is slightly different. The plasma does not always fall back but continues to rise at almost constant speed. A still unidentified force pushes this plasma and allows it to escape from the star. This force is the reason for the powerful stellar wind of Betelgeuse. It is the reason for the stardust that will one day form planets and perhaps life around another star.
This work is the result of six years of polarimetric measurements of Betelgeuse with the Narval and Neo-Narval instruments built by OMP and installed on the Bernard Lyot Telescope at the Pic du Midi. The observations and data analysis were performed by a team of researchers from OMP – IRAP and the University of Montpellier.
- Scientific paper : Three-dimensional imaging of convective cells in the photosphere of Betelgeuse? – Astronomy & Astrophysics by A. López Ariste, S. Georgiev, Ph. Mathias, A. Lèbre, M. Wavasseur, E. Josselin, R. Konstantinova-Antova et Th. Roudier, https://doi.org/10.1051/0004-6361/202142271
- Arturo Lopez Ariste, Arturo.Lopezariste@irap.omp.eu,
- Thierry Roudier, email@example.com