A CA-II LAMBDA-8662 INDEX OF CHROMOSPHERIC ACTIVITY - THE CASE OF 61 CYGNI-A

The stellar spectra obtained in our precise velocity program include t he Ca II infrared triplet line at lambda8662. Changes in the core flux of this line, quantified with our DELTAEW8662 index, reflect changes in stellar chromospheric activity. In our twelve years of Ca II observ ations for 61 Cygni A, we detect a solar-type cycle of 7.22 years and a rotational period of 36.21 days which confirm earlier results based on the H and K lines. The stability of the derived rotation period ove r twelve years suggests that the regions of chromospheric activity are either long-lived or formed within a limited longitude range.