Gravity-mode main-sequence asteroseismology of 16 open clusters and associations

Abstract

Coeval stellar populations offer a unique advantage for studying stellar physics because their members share a common age and broadly similar initial chemical composition, allowing the free parameters in stellar models to be constrained more efficiently. Meanwhile, asteroseismology, through the study of pulsation modes that propagate through stellar interiors, provides powerful constraints on internal structure and the physical processes operating beneath stellar atmospheres. The combination of coeval-population studies and asteroseismology therefore provides an unparalleled laboratory for testing and improving stellar evolutionary and structural models. Using light curves from the Kepler and TESS space missions, together with membership constraints based on Gaia astrometry, we identify g-mode period-spacing patterns in dozens of early-type ($T_{\rm eff} \gtrsim 7000\,\mathrm{K}$) main-sequence stars across 16 stellar groups. From these patterns, we infer near-core rotation rates $f_\mathrm{rot}$ and measure the asymptotic spacing $Π_0$ of g modes, tracing both angular-momentum transport and the evolution of the convective stellar cores. Using our homogeneous set of g-mode stellar-group members spanning a wide range of ages, we show that near-core rotation in early-type stars decreases with stellar evolution. We compare our results with existing model predictions. Our $Π_0$ measurements still show discrepancies with current stellar models for reasons that remain unclear, as reported in several previous studies. We also report two g-mode pre-main-sequence pulsators and three pulsating blue stragglers. Our sample provides a useful basis for calibrating stellar models in future ensemble asteroseismic studies of coeval stellar populations.