Spectra of plages on the sun and stars. I - Ca II H and K lines. II - The H I H-alpha line

Spectra of solar plages are used to define indices of plage properties in the Ca II H and K line region. Chromospheric and photospheric emission is examined and the details of height structure are noted. It is found that: (1) all spectral lines are weakened in plages except those of H I, He I, and some ionized metals; (2) the irradiation contribution from a plage is roughly constant throughout its disk passage; and (3) plage emission distorts spectral and photometric measures of stellar gravity, metallicity, and temperature.