Chromospheric activity to age relationship among Sun-like stars

Most recent studies have established the viability of deriving usable chromospheric ages for solar-type stars older than 600 Myrs up to at least 6 Gyr, providing that mass and metallicity effects are accounted for. In order to avoid the uncertainty associated with the age determination of field stars, I characterised the long-term evolution of chromospheric activity on Sun-like stars by combining an empirical model of their rotation evolution in intermediate-age open clusters with rotation-activity relationships. The results indicate that the chromospheric activity evolution of Sun-like stars with ages between 1 and 6 Gyr and masses between 0.7 and 1.1 M☉ is steeper than the relationship R’HK ~ age^{-0.5} generally used.