27 Arietis is a binary star[4] system in the northern constellation of Aries. 27 Arietis is the Flamsteed designation. It is a dim, yellow-hued star that is close to the lower limit of what can be viewed with the naked eye, having an apparent visual magnitude is 6.21.[2] The annual parallax shift of 11.64±0.12 mas[1] corresponds to a physical distance of approximately 280 light-years (86 parsecs) from Earth. It is advancing closer to the Earth with a heliocentric radial velocity of −122.7 km/s, and may come as close as 84 light-years in around 643,000 years.[2]
This appears to be a single-lined spectroscopic binary system with an orbital period of 130.7 days and an eccentricity of 0.366. It has an "a sin i" value of 10.00 ± 0.08 Gm (0.06685 ± 0.00053 AU), where a is the semimajor axis and i is the inclination to the line of sight from the Earth. This value provides a lower bound on the actual semimajor axis.[4] The visible component has a stellar classification of G8 III-IV Fe-2,[3] displaying mixed spectral traits of an evolvedsubgiant and a giant star, with a strong underabundance of iron. The CN bands of this star are very weak.[4]
^ abKeenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
^ abcdeGriffin, R. F. (October 2011), "Spectroscopic binary orbits from photoelectric radial velocities - Paper 220: 60 Piscium, 27 Arietis, EZ Ursae Majoris, and 4 Equulei", The Observatory, 131 (5): 294–314, Bibcode:2011Obs...131..294G.
