Western Slope Skies
11:25 am
Tue October 9, 2012

Albireo: Double Star

Albireo is a beautiful double star in the constellation Cygnus, the Swan.  If you heard the previous edition of Western Slope Skies, you learned about the Summer Triangle, which includes Deneb, the tail of Cygnus.  Albireo is the head of Cygnus and is dimmer than Deneb. 

Many stars have Arabic names dating back hundreds of years.  For example, Deneb means ‘tail.’  Because of the history involving several languages, the current name Albireo, while appearing to be Arabic, is actually meaningless.

Albireo is about 400 light years away.  To the naked eye, it appears to be a moderately bright single star.  However, even a small telescope reveals that it actually consists of two stars with different colors.  The gold star is Albireo A.  The blue star is Albireo B.   The colors you see may vary some, because each person does not always see faint colors the same.  If you attend a summer star gazing event, ask to see Albireo and decide what colors YOU observe.

Double stars can be either optical pairs or true binary pairs.  Optical pairs only appear to be close together, while true binary stars actually orbit around a common center of mass.  While Albireo A and B are 25-35 light years apart, we think they are a true binary system.

Albireo A is about 5 times as massive as our Sun and 70 times the Sun’s diameter.  The color of a star allows us to estimate the surface temperature. Based on that, we know that Albireo A is about 7000 degrees Farenheit.

Albireo B is about 3 times as massive as our Sun and 3 times the Sun’s diameter.  Albireo B is about 21,000 degrees Farenheit. 

Western Slope Skies is produced by members of the Black Canyon Astronomical Society

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