Delta Serpentis
Delta Serpentis, Latinized from δ Serpentis, is a binary star system system in the constellation Serpens, in its head (Serpens Caput). The light from the two stars in the system give a combined apparent magnitude of +3.80, which is bright enough to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 230 light years from the Sun. The system is moving closer with a radial velocity of ~42 km/s, and may come to within in 1.2 million years. The primary, component A, is a yellow-white F-type  subgiant with an apparent magnitude of +4.25. It is classified as a Delta Scuti type variable star and its magnitude varies by 0.04 with a period of 0.1557 days. Its binary companion, component B, is also an F-type subgiant which is slightly dimmer, with a magnitude of +5.2. A and B are separated by four arcseconds in the sky, and perform one orbit around their centre of mass once every 3,200 years. Naming. It was a member of indigenous Arabic asterism al-Nasaq al-Yamānī, "the Southern Line" of "al-Nasaqān" "the Two Lines", along with α Ser (Unukalhai ), ε Ser (Ba, Pa), δ Oph (Yed Prior), ε Oph (Yed Posterior), ζ Oph (Han) and γ Oph (Tsung Ching). According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "al-Nasaq al-Yamānī" or Nasak Yamani were the title for two stars :δ Ser as "Nasak Yamani I" and ε Ser as "Nasak Yamani II" (exclude α Ser, δ Oph, ε Oph, ζ Oph and γ Oph) 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 δ Serpentis, β Herculis, γ Herculis, κ Herculis, γ Serpentis, β Serpentis, α Serpentis, ε Serpentis, δ Ophiuchi, ε Ophiuchi and ζ Ophiuchi. Consequently, the Chinese name for δ Serpentis itself is (, ), representing the state Qin (秦) (or Tsin), together with θ Capricorni and 30 Capricorni (according to Ian Ridpath version) in "Twelve States" (asterism).