Sigma Draconis

Sigma Draconis (σ Dra, σ Draconis) is a 4.7-magnitude star located at a distance of 18.8 light-years from Earth in the constellation Draco. Its traditional name is Alsafi.

Sigma Draconis, the Bayer designation for this star, was established in 1603 as part of the Uranometria, a star catalogue produced by German celestial cartographer Johann Bayer. The proper name Alsafi was derived from Arabic Athāfi, erroneously transcribed from the Arabic plural Athāfiyy, by which the nomads designated the tripods of their open-air kitchens. It was the name of an association of this star, τ Dra and υ Dra. According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Athāfi or Alsafi were the title for three stars: σ Dra as Alsafi, τ Dra as Athāfi I and υ Dra as Athāfi II.

In Chinese, 天廚 (Tiān Chú), meaning Celestial Kitchen, refers to an asterism consisting of σ Draconis, δ Draconis, ε Draconis, ρ Draconis, 64 Draconis and π Draconis. Consequently, σ Draconis itself is known as 天廚二 (Tiān Chú èr, English: the Second Star of Celestial Kitchen.)

The star is a main sequence dwarf of spectral type K0 V, which has long served as a K0 V spectral standard star. Its classification as K0 V defines one of the rare anchor points of the Morgan–Keenan system that have remained unchanged since the original 1943 MKK Atlas. The stellar radius has been directly measured using interferometry with the CHARA Array, which yields a result of 77.8% of the Sun's radius. It has 87% of the Sun's mass, but the luminosity of this star is only 43% that of the Sun. The projected rotation rate (v sin i) is relatively low at 1.4 km/s. It is considered a slightly metal-poor star, meaning that it has a lower proportion of elements with masses greater than helium when compared to the Sun.