Observations of modulation and phase displacement of the stellar windin six red giant spectroscopic binaries.

Simultaneous spectroscopic measurements of stellar radial velocities and velocities of circumstellar (CS) Ca II K were obtained for six red giant spectroscopic binaries. For 4 Dra, RR U Min, Eta Gem, and Delta Sge, the CS velocities in Ca II K are found to follow the stellar radial velocity curves with different phase delays and amplitudes. The results reveal locations of the absorbing CS matter in the line of sight of less than 2 stellar radii for 4 Dra and of about 10 solar radii for RR U Min, Eta Gem, and Delta Sge.