# TESS Program G06163

Title: Moving Beyond The Classics: New Benchmark Star Clusters For Gyrochronology

PI: Curtis, Jason - Columbia University

Type: SMALL

Summary: Gyrochronology is a promising yet flawed clock. Recent studies of open clusters revealed that stars do not spin down continuously. Instead, once stars converge onto tight sequences of slowly rotating stars, they temporarily stall for an unknown but extended period of time. This phenomenon can heavily bias rotation-based ages for low-mass K and M dwarfs. We propose to conduct a census of stellar rotation in nearby (d<1000 pc) young (<1 Gyr) clusters, moving groups, and stellar streams with the goal of determining when these tight sequences form, and how long stars remain stalled, as a function of mass. We will use FFI data to extract light curves for ~12,500 stars spread across dozens of coeval groups for this purpose, including 1050 stars in 9 group receiving their first TESS data in C6.