Stellar Rotation Evolution in the Gaia Era: Revised Cluster Sequences and Prospects for the Post Main-Sequence
Rotation plays an important role in the life of stars, and offers a potential diagnostic to infer their ages and that of their planets. This idea is known as gyrochronology, and while potentially fruitful over a wide range of ages and masses, recent results have raised concerns regarding its applicability. In the first part of this talk, I will discuss the impact that removing the non-member contamination, by using the precise Gaia astrometry, has on the rotational sequences of open clusters. The revised sequences demonstrate that ground-based periods can be as constraining as space-based periods, illustrate that stars in the 1.0-0.6 Msun range inhabit a global maximum in terms of rotation periods (with potential consequences for habitability), and reveal that in the saturated domain the rotational distributions broaden, in contradiction with predictions from popular models. In the second part of this talk, I will discuss the importance of subgiant stars as empirical tests for stellar rotation, focusing on a sample of TESS CVZs subgiants. Results from a detailed characterization study demonstrate that these stars are ideal targets for precise age and mass determinations based on HR diagram location alone. The complementary roles played by classical and asteroseismic analyses will place stringent constraints on angular momentum evolution theories.