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  • Writer's pictureKGB

Albireo (The Beak Of the Swan).

No new gallery image this week, as the weather during July has tried to emulate the mythical flood of Gilgamesh mentioned in the Epic of Gilgamesh, an epic poem from ancient Mesopotamia. One thing is for certain the rain has not been a myth, but it has been epic. One clear night in the whole of July for our area. Yes, this is the usual UK summer and nothing to do with "climate change".

So, on that clear night I imaged the Cocoon Nebula (see my image of that here: ). I also imaged for 5 one minute exposures, Albireo, the famous double star also in Cygnus, and the subject of this blog.

Albireo. Double star in Cygnus. 5 x 60 seconds. Imaged by me the author!

Albireo (Beta Cygni) is the primary component in a multiple star system located in the constellation Cygnus. It appears as an optical double star in small telescopes. With an apparent magnitude of 2.90, it is the fifth brightest star in Cygnus and the faintest of the stars that form the Northern Cross. Albireo lies at an approximate distance of 415 light years from Earth. It is one of the best-known colour contrasting double stars in the sky and a firm favourite for amateur astronomers, just about everywhere!

Albireo appears as a single star to the naked eye and is only resolved into a visual binary star system in a small telescope or medium size binoculars. The two components are designated Beta Cygni A or Beta1 Cygni and Beta Cygni B or Beta2 Cygni. The brighter of the two – Beta Cygni A – appears yellow/red, while the fainter component – Beta Cygni B – always appears blue. The two stars are separated by 34.3 arcseconds, but there are uncertainties as to whether they are a physical pair or merely lie in the same line of sight. If they do form a binary system, they would take at least 75,000 years to complete an orbit. However, as the stars do not share a common proper motion across the sky, this is probably a chance alignment, and the stars are not gravitationally bound. This seems to be backed up by the Gaia mission data.

The separation between the two stars has not changed in over 260 years and the position angle of Albireo B has only changed slightly. However, the stars do lie at different distances. The Hipparcos mission placed Albireo A at 434 light years from Earth and Albireo B at 401 light years. However, the data from the Gaia mission indicates distances between 330 and 390 light years for both stars. Even though it has the Bayer designation Beta Cygni, Albireo is actually fainter than Sadr (Gamma Cygni), Fawaris (Delta Cygni), and Aljanah (Epsilon Cygni).

Albireo A, the brighter star is a red supergiant star, about 5 times the mass of the sun. It outshines its fainter companion, a hot main sequence star that’s 2.7 times the sun’s mass. Albireo B is a blue-white star of the spectral type B8Ve. It has an apparent magnitude of 5.11. The star has a radius 2.59 times that of the Sun and a mass of 3.7 solar masses. In medieval Arabic astronomy, Albireo was known as Al Minhar al Dajajah, meaning “The Hen’s Beak.” The name referred to the star’s position in the constellation. (Albireo is still sometimes known as the “Beak Star,” as it marks the beak of the celestial Swan.) Note the position of Albireo in the star chart above. This name appeared in the Egyptian astronomer Al Achsasi Al Mouakket’s Calendarium in the 17th century. It was translated into Latin as Rostrum Gallinae.

Artists impression of Albireo.

One interesting fact about Albireo, that no one alive now will ever see, unless there is life after death and we still inhabit this dimension of the Universe, is that Albireo will be the brightest star in the sky around the year 3,870,000, when it comes within 80 light years of our solar system. At its peak (around the year 4,610,000), it will shine at magnitude -0.52, which is a little fainter than Canopus is now. Canopus is the brightest star in the southern constellation of Carina and the second-brightest star in the night sky after Sirius. So, with that sobering thought, I will end this edition of my blog. I hope you have enjoyed this rather informative diatribe and please let me know with your comments. Thanks for reading and I will see you next weekend as usual..

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