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Red giant seismology: large-scale measurements of the core rotation and stellar inclination, and new constraints on the angular momentum transport through modelling

Charlotte Gehan
IA

Abstract
Red giant stars have proved to be asteroseismic targets of choice. Indeed, we have a direct view on their core through mixed modes, which is not the case for solar-type pulsators on the main-sequence, such as the Sun. Among others, mixed modes allow us to probe the red giant core rotation. This is a unique opportunity to test stellar physics because although rotation is a fundamental ingredient of stellar structure and dynamics, understanding its evolution is still challenging. Models indeed predict central rotation rates at least ten times faster compared to seismic measurements. Such strong discrepancies between models and measurements reveal that angular momentum is transported in stellar interiors, and that the physical mechanisms at work are not yet fully understood. I will explain how large-scale measurements of the red giant core rotation could be derived, and how these results can bring new constraints on the angular momentum transport efficiency using stellar modelling. I will also present large-scale measurements of the inclination angle of the red giant rotation axis derived using mixed-modes, that are crucial to study planetary formation and dynamics.

2020 February 05, 13:30

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

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