Gamma Andromedae

Gamma Andromedae (γ Andromedae, abbreviated Gamma And, γ And) is the third-brightest point of light in the constellation of Andromeda.

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, also named Almach) next to a dimmer, indigo-blue star (γ² Andromedae), separated by approximately 10 arcseconds. It is often considered by stargazers to be a beautiful double star with a striking contrast of color. 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, approximately 350 light-years from the Earth.

γ¹ Andromedae is a bright giant star with a spectral classification of K3IIb. It has an apparent visual magnitude of approximately 2.26.

5.5 (B)
6.3 (C)

   (spectroscopic binary)
A0V (C)

γ² Andromedae, with an overall apparent visual magnitude of 4.84, is 9.6 arcseconds away from γ¹ Andromedae at a position angle of 63 degrees.

In October 1842, Wilhelm Struve found that γ² Andromedae was itself a double star whose components were separated by less than an arcsecond. 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. They have an orbital period of about 64 years. 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.