A staple of the summer sky, the constellation of Cygnus the Swan is an easily recognizable grouping of stars that could be seen as resembling a swan in flight, with its slender neck stretched out. The bright bluish star located where the tail feathers would be is Deneb. Being the brightest star in this constellation, it is labeled as Alpha Cygni. At the other end (the “beak”) is the second brightest star, Beta Cygni, also known as Albireo. Albireo is visible to the naked eye if the sky is dark and there is not much light pollution. The peculiarity of Albireo is that, upon observation with any modest telescope, it becomes apparent that it is not a single star but that it is actually comprising of two stars very near each other.
It is not well understood if this vicinity is real or is just a trick of parallax and perspective but the “claim to fame” of Albireo is the striking difference in color of these two stars. Beta Cygni A is the brightest of the two and appears to be a deep yellow, while Beta Cygni B is blue green. Heterochromic stars, anyone?
The image shown was taken during the night of November 11 2021.
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stars, Beta Cygni, constellations