Gamma Andromedae is Almach, one of the most beautiful double stars in the night sky. It has an apparent magnitude of 2.1 and is the third brightest star in the constellation of Andromeda.

In a telescope, Almach can be seen to be a wonderfully colored gold and blue pair of stars separated by 9.58 arcseconds. The colors in this pair rival that of Albireo (Beta Cygni).

The primary star (Gamma 1 Andromedae, also known as the A component) is a spectral-type K3 giant with a golden-yellow color that shines at magnitude 2.26. The secondary star (Gamma 2 Andromedae), at a position angle of 63 degrees, is a magnitude 4.84 A-type main sequence star. Their combined brightness gives Almach its visual magnitude of 2.1.

Gamma 2 Andromedae is itself a double star with components labeled B and C that are separated by less than 1 arcsecond. Their individual magnitudes are 5.5 and 6.3. Their combined brightness give Gamma 2 Andromedae its brightness of magnitude 4.84.

Subsequent spectroscopic observations in 1957 to 1959 revealed that B is another double star, making the entire Gamma Andromedae system a quadruple star.

The Almach star system is located 350 light-years away.

Johann Tobias Mayer discovered that Almach was a double star in 1778, and Wilhelm Struve discovered that Gamma 2 Andromeda was a double star in 1842.

North is to the top in the above image.

Gamma Andromedae Catalogs: 57 And SAO 37734 HD 12533 HIP 9640 ADS 1630 WDS 02039+4220 TYC 2837=2311-1 Common Name: Almach, Almaak Object Type: Multiple Star Magnitude: 2.1 / Individual Stars Mag 2.26, 4.84 Separation: 9.58" Constellation: Andromeda Image Field Centered At: RA: 02h 03m 54s Dec: +42° 19' 47"