Delta Serpentis


Delta Serpentis, Latinized from δ Serpentis, is a quadruple star system system in the constellation Serpens, in its head. The light from the four 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 system consists of a pair of binary stars separated by 66.6 arcseconds. 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 a F-type subgiant which is slightly dimmer, with a magnitude of +5.2. A and B are separated by four arcseconds on the sky, and perform one orbit around their centre of mass once every 3200 years.The 13th magnitude star component C and 14th magnitude component D form the second binary sub-system. They are separated from each other by 4.0 arcseconds.

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, ε Ser, δ Oph, ε Oph, ζ Oph and γ Oph.
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
In Chinese, 天市右垣, meaning Right Wall of Heavenly Market Enclosure, refers to an asterism which is represent eleven old states in China which is marking 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 天市右垣六, represent the state Qin , together with θ Capricorni and 30 Capricorni in Twelve States.