                        Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                              2022 February 24

                            Beautiful Albireo AB
                    Image Credit & Copyright: Robert Eder

   Explanation: Beta Cygni is a single bright star to the naked eye. About
   420 light-years away it marks the foot of the Northern Cross, famous
   asterism in the constellation Cygnus. But a view through the eyepiece
   of a small telescope will transform it into a beautiful double star, a
   treasure of the night sky in blue and gold. Beta Cygni is also known as
   Albireo, designated Albireo AB to indicate its two bright component
   stars. Their visually striking color difference is illustrated in this
   telescopic snapshot, along with their associated visible spectrum of
   starlight shown in insets to the right. Albireo A, top inset, shows the
   spectrum of a K-type giant star, cooler than the Sun and emitting most
   of its energy at yellow and red wavelengths. Below, Albireo B has the
   spectrum of a main sequence star much hotter than the Sun, emitting
   more energy in blue and violet. Albireo A is known to be a binary star,
   two stars together orbiting a common center of mass, though the two
   stars are too close together to be seen separately with a small
   telescope. Well-separated Albireo A and B most likely represent an
   optical double star and not a physical binary system because the two
   components have clearly different measured motions through space.

                     Tomorrow's picture: mars with moxie
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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