2010MNRAS.402.1675G

HR 3222 is a late-type giant star that has long been known as a spectroscopic binary. A single-lined orbit is readily found; it has a period of 955 d and an eccentricity of 0.33. The spectrum is noticeably composite, especially at short wavelengths; radial-velocity traces show a weak secondary dip that is broadened by a rotational velocity of 18 km/s. We employ high-dispersion spectroscopy and uncover the secondary spectrum by subtracting from the observed composite one the spectrum of the K0 giant β Gem; the residue is a metallic-line star of type kA8hF2mF4, and measurements of its wavelength displacement from the primary spectrum give a more reliable radial velocity for that component than seems achievable from radial-velocity traces. The mass ratio is 1.20 ±0.03. The stars can both be placed on an evolutionary track corresponding to an age of 1.4 Gyr. The fact that the secondary component is a metallic-line star cannot be attributed to the result of tidal effects in this binary system.