Omicron Andromedae

Omicron Andromedae (ο And, ο Andromedae) is a star system in the constellation Andromeda. It is approximately 692 light years from Earth. The system as a whole is classified as a blue-white B-type giant, with a mean combined apparent magnitude of +3.62.

Characteristics
Omicron Andromedae is a multiple star containing at least four components. It is thought to consist of two close pairs in a wider orbit, making a four-star system. This star system has a peculiar velocity of 34.5 ± 5.9 km/s.[12]

The components A and B were first resolved in 1949, when they were reported to be separated by less than 0.1".[14] In 1975 they were separated by 0.375"[10] and by 2014 by only 0.21".[15] An orbit has been derived with a period of 117 years.[8]

In 1975, a companion was discovered by speckle interferometry only 0.05" from component A.[4] Components Aa and Ab orbit every 5.6 years.[8]

A fourth component in the system was suspected and in 1988 it was confirmed. Although a clear 33.01 day period was seen, it was unclear which component the fourth star was in orbit with.[10] Eventually, it was settled that component B was a close spectroscopic binary including the fourth star.