This is an astrometric binary star system. The best fit to the radial velocity data yields an orbital period of roughly 13,770 days (37.7 years) with an eccentricity of around 0.28. The semimajor axis of their computed orbit is about 13 au, or 13 times the distance of the Earth from the Sun.[7] The primary, component A, is an evolvedK-typesubgiant star[8] with a stellar classification of K2 V Fe-1.3 CH-0.8,[3] where the suffix notation indicates the absorption lines of iron and the carbon-hydrogen bond are abnormally weak.[10] However, classifications earlier than Gray et al. (2006) consistently showed it as type G5 IV,[7] matching the subgiant categorization.
^ abcJohnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J.
^Keenan, P. C. (1985), "The MK classification and its calibration", Proceedings of the Symposium, calibration of fundamental stellar quantities, vol. 111, Dordrecht: D. Reidel Publishing Co., pp. 121−135, Bibcode:1985IAUS..111..121K.