Almach: Binary Star Jewel in the Heavens

Almach is a binary star system in the constellation Andromeda. It’s best viewed in the autumn. It’s also known as Gamma Andromedae.

Double stars of contrasting colors are strikingly beautiful. And while most observers may first think of the famous Andromeda Galaxy, Almach is an equally worthy destination in the constellation Andromeda on fall evenings.

Physicist Johann Tobias Mayer discovered this pair in 1778. Since then, skywatchers have enjoyed the beautiful contrast of γ¹ Andromedae, with its golden color to γ² Andromedae, which looks like a deep blue sky. They are 1,130 AU apart.

Another fun fact: Almach may appear as one star, but in fact, it’s not just a double but a quadruple star system.

My Observations

This pair truly rivals the stunning Alberio double! In fact, I may like this double even more. The color contrast showing through my scope tonight is remarkable. The top star appears to be orangish/red, while the bottom is blue

Key Stats

Constellation	Andromeda
Best Viewing	Autumn
Visual Magnitude	+2.17 | +5.02
Separation	9.4″ | 1250 AU
Position Angle	65°
Absolute Visual Magnitude	-3.2
Distance from Earth	430 ly
Orbital Period	63.7 yrs.
Milky Way Location	Orion Spur
My Viewing Grade	A
Designations	SAO 37734, HIP 9640, Gamma Andromedae, Almaak, γ Andromedae, Struve / STF 205

Sources

Photo of Almach is licensed under the Creative Commons Attribution-Share Alike 4.0 International license and attributed to the author with name of NVN271.