Alberio Classic Example of Binary Star

The constellation Cygnus the Swan is best known for the star Deneb (Alpha Cygni) which marks the tail of the swan.  But observers using binoculars or a small telescope will want to turn to the other end of the swan, to Alberio at the swan's nose.

To the unaided eye Alberio looks like any other star.  But with binoculars or a telescope Alberio reveals itself to be a binary star system, two stars orbiting each other.  The pair are beautiful because of the striking contrast in color.  One is a deep gold color and the companion is a bright blue.

The color of the stars indicates their temperature.  The gold star is much like our own sun, with a moderate temperature, about 4,000 K.  The blue star is hot, over 13,000 K.  

Alberio is one of the classic examples of a double star; singular to the unaided eye, but stunning through a little magnification.  

Alberio (Beta Cygni) created by the Author using Stellarium.