L-S periodograms of the RV measurements, the Hipparcos photometric measurements, the H_α EW variations, and the bisector variations for 8 UMi (top to bottom panel). The vertical dashed line shows the location of the period of 93 days. Top panel: the solid line is the L-S periodogram of the RV measurements for five years, and the periodogram shows a significant power at a period of 93.4 days. The dashed line shows the periodogram of the residuals after removing of the main period fit from the original data. The horizontal dotted line indicates a FAP threshold of 1 × 10^-2 (1%).