THE RADIAL-VELOCITY VARIABILITY OF THE K-GIANT BETA-OPHIUCHI .2. LONG-PERIOD VARIATIONS

Precise relative radial velocity measurements (sigma similar to 20 m s (-1)) of the K giant beta Oph are presented and these show variations with a period of 13.05 days. Rotational modulation, low-mass companion s, and radial velocity variations can be excluded as an explanation fo r these variations. Most likely this period results from a nonradial g -mode. A period analysis on the residual radial velocities after subtr acting the contribution of the dominant period yields a long-term peri od of 142.3 days and a short-term period of 0.2589 +/- 0.005 days. The latter is consistent with previous works by Hatzes & Cochran. The lon g-term period, if real, most likely arises from rotational modulation by surface features, although the presence of a planetary companion ca nnot be excluded at the present time.