2006A&A...454..839K

We present the first results from a high-precision radial velocity study of the K2III giant star {alpha} Ari. Observations were acquired over 6 nights in 2004 using the new high-resolution spectrograph BOES (Bohyunsan Observatory Echelle Spectrograph) of the 1.8-m telescope. A high radial-velocity precision was achieved by using the high-resolution (R=90000) mode of BOES and an iodine gas absorption cell. The radial velocity measurements made during but on shorter time-scales and with a lower amplitude. Two probable periods fit the radial velocity measurements from the second run reasonably well: 0.185days or an alias of 0.256days. The shorter period coincides with the secondary one found in the earlier measurements. We conclude that, similar to other K-giant pulsating stars, {alpha} Ari shows unstable acoustic pulsations or mode switching on time scales of tens of days. The calculated pulsation constants for the dominant 0.571-day period is consistent with third-overtone pulsations, while the secondary periodicity found in both data runs corresponds to a high overtone (n≥12).