High-precision radial velocities of Arcturus measured on 43 occasions from 1981 through 1985 show a 500 m s _1 range. This range is much larger than the external errors of our observations (typically 13 m s" 1 ) confirming the radial-velocity variability of Arcturus that has been previously reported by our group arid others based on shorter observational time spans. Using a nonlinear least-squares technique, we have determined a number of multiperiodic models which give a good representation of our velocities simultaneously with those of Smith, McMillan, and Merline (1987). The small-amplitude short-period components of these models could represent the Arcturus analog of the solar five-minute oscillations. Confirmation of this interpretation will require additional observations to help sort out the aliasing problems for these components. Regardless of which aliases are chosen to represent the short-period oscillations, our best-fitting models require the period of the largest-amplitude component to be 640 days or longer. A long-period component could be caused by some surface effect such as convective motions or modulation of the radial velocity by rotation. Alternatively, a long-period component could be caused by motion of Arcturus as it orbits with a low-mass companion around their common center of mass.
ɛ Per (45 Per, HR 1220, HD 24760, ADS 2888A) is a star which was used for years as a spectrophotometric and MKK classification standard. Nowadays it is known as an archetype of early-type line-profile variables (LPV). The variations are so pronounced that they were misinterpreted for a composite spectrum (B0.5+A2) and the star was even reported to be a double-lined spectroscopic binary (Petrie 1958). Since 1983, the characteristics of line-profile variability in the spectrum of ɛ Per have been intensively studied (Bolton 1983, Smith 1985, Gies & Kullavanijaya 1988). The recent investigations of RV variations of ɛ Per led to the conclusion that ɛ Per is a spectroscopic binary with a period of about 14.05 days and a rather eccentric orbit (Harmanec & Tarasov 1990). The issue of the binary nature (with a very eccentric orbit) is of utmost importance since it could be causally related to the extremely large observed line-profile variations (e.g., Polfliet & Smeyers 1990, Tassoul & Tassoul 1992).
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