X-ray activity in stellar clusters Original Research Article

Stellar cluster observations play a key role in understanding the evolution of coronal activity with rotation and time. Although the general picture of a decline in coronal X-ray emission from young to old clustess is well-established, many questions remain. These include the apparent absence of cyclic X-ray variability in active solar-type stars, the Hyades-Coma-Praesepe puzzle, and the recent evidence for “supersaturation” in very young clusters. I will review these issues in the context of both stellar and relevant solar observations.