Stars: chromospheres Stars: activity 12 Stars 8 Stars: late-type 8 Astrophysics 4 Calcium 4 Chromophores 4 Chromospheric activity 4 Lomb-scargle periodogram 4 Spectrum analysis 4 Stars: flare 4 Stars: individual 4 Stars: solar types 4 Sun: chromosphere 4 Activity proxies 2 Atomic processes 2 Binaries: spectroscopic 2 Chromosomes 2 Continuum mechanics 2 Correlation methods 2 Cyclic variation 2 Detecting activities 2 Earth (planet) 2 Hydrogen 2 Iron compounds 2 Line: formation 2 Line: profiles 2 Magnetic flux 2 Measurement theory 2 Medium-resolution echelle spectra 2