DELTA SERPENTIS

'Delta Serpentis' (δ Ser / δ Serpentis) is a star system in the constellation Serpens, in its head (Serpens Caput). It also has the traditional name 'Qin' or '''Chin''', from the Mandarin 秦朝, Qín Cháo, referring to the Qin Dynasty. It is approximately 210 light years from Earth. The light from the four stars in the system give a combined apparent magnitude of +3.80(combined).
The system consists of a pair of binary stars separated by 66 arcseconds. The primary component, 'Delta Serpentis A', is a yellow-white F-type subgiant with an apparent magnitude of +4.2. It is classified as a Delta Scuti type variable star and its magnitude varies by 0.04 with a period of 0.134 days. Its binary companion, 'Delta Serpentis 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 14th magnitude stars 'Delta Serpentis C' and 15th magnitude 'Delta Serpentis D' form the second binary sub-system. They are separated from each other by 4.4 arcseconds.