Quentin Noraz (University of Oslo): The Sun in Time: Recent advances in understanding the magneto-rotational evolution of solar-type stars

Thursday 16 Oct 2025, 14:00 → 15:00 Europe/Stockholm

90101

Title: The Sun in Time: Recent advances in understanding the magneto-rotational evolution of solar-type stars
Speaker: Quentin Noraz
Affiliation: University of Oslo
 

Abstract:

 The magnetic fields of solar-type stars are driven by a dynamo resulting from the combined action of small-scale turbulent convection and large-scale differential rotation (DR). This coupling produces magnetic variability across scales, from decadal cycles such as the solar 11-year cycle to long-term secular evolution. The strength and geometry of DR within the convection zone are key in setting the dynamo properties, yet how these evolve as stars age remains uncertain.

Along secular timescales, rotation and magnetism are tightly linked. Magnetic fields shape stellar winds and the resulting angular momentum loss, driving stellar spin-down along the main sequence, while rotation governs magnetic activity. This nonlinear feedback loop gives rise to the gyrochronology relation, although old solar-type stars appear to rotate faster than predicted by the canonical Skumanich law (Ω ∝ t⁻¹ᐟ²).

In this presentation, I will present some of the recent numerical efforts to model this magneto-rotational evolution across scales by placing the Sun back in its stellar context. I will further discuss current challenges faced in this framework, emphasizing how simulations and observations together can help improve our understanding of cool-star magnetism.