The temperature, granulation, and chromospehric emission of tau Ceti (HR 509, HD 10700, G8 V, B-V = 0.72) in the 1984-1992 interval are studied for magnetic-cycle type variations. Yearly-mean temperature measurements are determined to +/- 3-4 K using ratios of spectral line depths, and show no systematic variations over the 9 yr interval. Granulation is monitored using the asymmetries of spectral lines. There is some indication of systematic variation in velocity span, but this variation is not well established. The Ca II H and K line emission, although weak by stellar standards, may show two cycles of variability in the 1970-1992 time span with a period of approximately = 11 yr. No rotation modulation is seen in any of the parameters, but the very narrow spectral lines of tau Cet points to a nearly pole-on orientation so that none would be expected.
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Gray et al. (1994) studied this question.