OBSERVATIONS OF ACTIVE-CHROMOSPHERE STARS .4. PHOTOMETRY AND SPECTROSCOPY OF CF-OCTANTIS (HD-196818)

We present photometry and spectroscopy of the single, K-type, active-c hromosphere star CF Octantis (=HD 196818), from 1982 to 1986. The phot ometric data show the 20-d rotation period seen previously, and also d emonstrate that the light curve is variable on time-scales of a few mo nths, which we ascribe to variations in the properties of starspots. W e postulate that a temporary dimming of minimum light seen in mid-1983 was a result of the appearance and later disappearance of a relativel y small spot or spot group, which had a lifetime between 10 and 24 mon ths. The main spot appeared relatively stable during the interval of o ur observations, with a lifetime of at least 3 years. Our radial veloc ity data are consistent with the results of other work in that no vari ations above observational scatter are seen. Both the Ca K and H alpha emission are variable, with tentative evidence for the latter that a lower emission level occurred near the phase of photometric maximum, a lthough the spectroscopic and photometric data were not contemporaneou s. The lithium abundance is found to be log N(Li)=0.45+/-0.15. The sta r may have evolved from a rapidly rotating A-F main-sequence star.