CaII H&K emission distribution of ~ 120 000 F, G and K stars in LAMOST DR1

We present chromospheric activity index S HK measurements for 119 995 F, G and K stars with high signal-to-noise ratio (S/N > 80) spectra, extracted from LAMOST DR1 in SDSS g band. The index δS for each of these stars is calculated by the difference between its S HK value and the baseline determined from very inactive stars. The effect of metallicity on measurement of δS varies with stellar T eff . No evident Vaughan-Preston gap appears in our sample. The relation between δS and vertical distance from the Galactic plane is determined for stars with T eff 5500 K, similar δS levels appear in both young and old cluster stars, which supports Pace’s suggestion that caution should be exercised when deriving the age of a single star by using its chromospheric activity. Finally, we investigate the relation between δS and the kinematics of our sample.