Duplicity among Stars with Strong Chromospheric CA II Emission Lines: A Statistical Survey

Using high-dispersion coudé spectrographs the authors have made multiple observations of 38 stars, all of which have strong emission-line core reversals in their Ca II H and K lines relative to the majority of stars of their same spectral type and luminosity class. Most of the sample stars are on the main sequence.The authors have found four possible (new) close binaries in their sample based upon detected variations of radial velocity. Comparing these results with similar studies of active stars, the authors find that duplicity may, in special circumstances, be sufficient but is not a necessary condition to generate magnetically induced chromospheric activity.