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First characterization of the precise structure of red-giant star cores

Mathieu Vrard
Université Côte d'Azur, France

Red giants are stars in the late stages of stellar evolution. Because they have exhausted the supply of hydrogen in their core, they burn the hydrogen in the surrounding shell. Once the helium in the core starts fusing, the star enters the clump phase. Since the launch of the CoRoT and Kepler satellites, it became possible to analyze their deep layers with asteroseismology. However, obtaining precise constraints on specific regions, particularly their core structure, still remained particularly difficult. Here I will present a summary of the first precise characterization of specific layers in the core of red giant objects that was realized with the asteroseismology team of Porto (IA). We found evidence for large core structural discontinuities present at the boundary of the radiative core for 23 clump objects. The characterization of those discontinuities implies that the region of mixing beyond the convective core boundary has a radiative thermal stratification. These stars are otherwise similar to other clump stars, which may indicate that the building of the discontinuities is an intermittent phenomenon.

2023 June 21, 13:30

Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto

Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia