Almach

Gamma Andromedae (γ Andromedae, abbreviated Gamma And, γ And) is the third-brightest point of light in the constellation of Andromeda. It is a multiple star system approximately 350 light-years from the Earth.

In 1778, Johann Tobias Mayer discovered that γ Andromedae was a double star. When examined in a small telescope, it appears to be a bright, golden-yellow star (γ1 Andromedae or γ Andromedae A, officially named Almach /ˈælmæk/, the traditional name for the entire system)[7][8] next to a dimmer, indigo-blue star (γ2 Andromedae or γ Andromedae B), separated by approximately 10 arcseconds. It is often considered by stargazers to be a beautiful double star with a striking contrast of color.[9] It was later discovered that γ2 Andromedae is itself a triple star system. What appears as a single star to the naked eye is thus a quadruple star system.

Characteristics
γ1 Andromedae (A component) is a  bright giant star with a spectral classification of K3IIb. It has an apparent visual magnitude of approximately 2.26.[1]

γ2 Andromedae (BC component), with an overall apparent visual magnitude of 4.84,[21] is 9.6 arcsecondsaway from γ1 Andromedae at a position angle of 63 degrees.[6]

γ1 and γ2 have an orbital period of approximately 5,000 years.[5]

In October 1842, Wilhelm Struve found that γ2 Andromedae was itself a double star whose components were separated by less than an arcsecond.[13] The components are an object of apparent visual magnitude 5.5, γ Andromedae B, and a type-A main sequence star with apparent visual magnitude 6.3, γ Andromedae C.[21] They have an orbital period of about 64 years.[24] Spectrograms taken from 1957 to 1959 revealed that γ Andromedae B was itself a spectroscopic binary, composed of two type-B main sequence stars orbiting each other with a period of 2.67 days.