Beta Serpentis
Beta Serpentis, Latinized from β Serpentis, is a binary star system in the constellation Serpens, in its head (Serpens Caput). It is visible to the naked eye with a combined apparent visual magnitude of +3.65. Based upon an annual parallax shift of 21.03 mas as seen from Earth, it is located around 155 light years from the Sun. The system is a member of the Ursa Major Moving Group. Components. The visual magnitude +3.68 primary, component A, is either an ordinary A-type main-sequence star or somewhat evolved subgiant with a stellar classification of A2 V or  A2 IV, respectively. The star is about 267 million years old with nearly double the mass of the Sun. It is spinning rapidly with a projected rotational velocity of 207 km/s. The secondary component, visual magnitude 9.7 B, lies at an angular separation of 30.6 arc seconds. It is a main-sequence star with a class of K3 V. There is a magnitude +10.98 visual companion, designated component C, located 202 arcseconds away. Nomenclature. It was a member of indigenous Arabic asterism al-Nasaq al-Sha'āmī, "the Northern Line" of "al-Nasaqān" "the Two Lines", along with β Her  (Kornephoros), γ Her (Hejian, Ho Keen) and γ Ser (Zheng, Ching). According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "al-Nasaq al-Sha'āmī" or Nasak Shamiya were the title for three stars :β Ser as "Nasak Shamiya I", γ Ser as "Nasak Shamiya II", γ Her as "Nasak Shamiya III" (exclude β Her). In Chinese, (), meaning "Right Wall of Heavenly Market Enclosure", refers to an asterism which represents eleven old states in China and which marks the right borderline of the enclosure, consisting of β Serpentis, β Herculis , γ Herculis, κ Herculis, γ Serpentis, δ Serpentis, α Serpentis, ε Serpentis, δ Ophiuchi, ε Ophiuchi and ζ Ophiuchi. Consequently, the Chinese name for β Serpentis itself is (, ), represent Zhou (周) (possibly Chow, the dynasty in China), together with η Capricorni and 21 Capricorni in "Twelve States" (asterism).