Albireo

Common card · No. 259667

Albireo is a double star in the southern constellation of Cygnus. It has the Bayer designation Beta Cygni. The International Astronomical Union uses the name "Albireo" specifically for the brightest star in the system. Although designated 'beta', it is fainter than Gamma Cygni, Delta Cygni, and Epsilon Cygni and is the fifth-brightest point of light in the constellation of Cygnus. Appearing to the naked eye to be a single star of magnitude 3, viewing through even a low-magnification telescope resolves it into its two components. The brighter yellow star, itself a very close trinary system, makes a striking colour contrast with its fainter blue companion.

Read on Wikipedia · Image Cygnus_constellation_map.png: Torsten Bronger derivative work: Kxx (talk), CC BY-SA 3.0