Zeta Arietis
Zeta Arietis is a star in the northern constellation of Aries. Its name is a Bayer designation that is Latinized from ζ Arietis, and abbreviated Zeta Ari or ζ Ari. This star is dimly visible to the naked eye with an apparent visual magnitude of +4.87. Based upon an annual parallax shift of, the distance to this star is approximately. It is receding from the Sun with a radial velocity of +7 km/s.
This is an A-type main sequence star with a stellar classification of A1 V. It is an estimated 333 million years old and is spinning rapidly with a projected rotational velocity of 133 km/s. Zeta Arietis has 2.4 times the mass of the Sun and 3.0 times the Sun's radius. It is radiating 66 times the luminosity of the Sun from its photosphere at an effective temperature of 9,528 K, giving it the characteristic white-hued glow of an A-type star.
Name
This star, along with δ Ari, ε Ari, π Ari, and ρ3 Ari, were Al Bīrūnī's Al Buṭain, the dual of Al Baṭn, the Belly. According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Buṭain was the title for five stars: δ Ari as Botein, π Ari as Al Buṭain I, ρ3 Ari as Al Buṭain II, ε Ari as Al Buṭain III, and ζ Ari as Al Buṭain IV.In Chinese, 天陰, meaning Yin Force, refers to an asterism consisting of ζ Arietis, 63 Arietis, δ Arietis, τ Arietis and 65 Arietis. Consequently, the Chinese name for ζ Arietis itself is 天陰二