V381 Cephei

V381 Cephei (HR 8164) is a triple star system in the northern constellation of Cepheus. Its apparent magnitude is slightly variable between 5.5 and 5.7.

System
V381 Cephei is a visual double star with components A and B separated by 4.6". The primary is HD 203338 and the secondary is the magnitude 9.2 HD 203339.

HD 203338 is itself a spectroscopic binary with components Aa and Ab orbiting every 280 years. It forms a VV Cephei-type binary system with a hot companion which is accreting mass from the primary. The long period means that it exhibits fewer peculiarities than other VV Cephei binaries.

Properties
Component Aa is a red supergiant and its close companion is a B2 main sequence star. The supergiant is a pulsating variable with a small amplitude and poorly defined period. It is generally given spectral class qualifiers indicating peculiarities and emission, which may be associated with the disc around the hot secondary.

Component B, HD 203339, is a B3 main sequence star with a mass around.