The evolution of rotation and activity for FGK dwarfs in LAMOST– Kepler field

This is the authors' abstract. We don't add key points for this paper.

Based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Gaia surveys, we compute the convective turnover time-scales of stars with the mass range of 0.7–1.4 M using the mesa code. We provide a catalogue of 10 400 FGK dwarfs in the LAMOST–Kepler field, including Rossby number Ro, rotation periods Pᵣₒₜ, photometric activity proxy Sₚₕ, and chromospheric activity index R⁺HK. The relations between both activity indices and Ro can be characterized by the saturated, decay, and flat regimes. In the flat regime, the Sₚₕ remains nearly constant while the R⁺HK exhibits an enhancement as Ro increases for F dwarfs. In the decay regime, all stars exhibit uniform decay behaviour in both Sₚₕ–Ro and R⁺HK–Ro relations. In the saturated regime, GK dwarfs display a significant Sₚₕ dip, while only K dwarfs exhibit a pronounced R⁺HK dip. Moreover, the Ro range of this dip aligns with the spin-down stalling observed in open cluster studies, suggesting a possible origin in the core–envelope coupling senario. Additionally, the results show that the Sun falls within the transition from decay to flat regime in both activity-Ro diagrams. The results will improve the understanding of the connection among convection, rotation, and magnetic fields for solar-like stars.