Albireo – a colourful variable double star system in Cygnus. It’s naked eye appearance is of a magnitude 3.0 single star but it only takes low power magnification to resolve into two bright stars.

Albireo A is an orange Class K3 giant of five solar masses and fifty solar diameters.

Albireo B is a blue Class B8 main sequence star of three to four solar masses.

Due to  their high actual separation, it is yet to be confirmed that these two stars are orbiting as a single star system. Albireo A is itself a double star with another companion at a distance of 40 AU.


Object Details:

Albireo, Beta Cygni, SAO 87301.
Visual magnitude: +3.1 and +4.7.
Apparent separation: 34.3 arc-sec.
Actual separation: 4570 AU or 26 light days.
Distance: 380-430 light years.


Exposure: 1 x 30 sec ISO 500.
Date: 2017-09-09.
Location: Leumeah, NSW.
Sky: outer suburban sky, some thin high cloud.
Processing: Canon DPP & GIMP.
Cropping: yes.

Imaging telescope: Skywatcher Esprit 120ED Super APO triplet refractor.
Focal length: 840mm, focal ratio: f/7.
Imaging camera: Canon EOS 60D.
Guiding telescope: Orion ShortTube 80mm Achromatic doublet.
Focal length: 400mm, focal ratio: f/5.
Guiding camera: Orion StarShoot.
Guiding control: PHD2 software.
Telescope mount: SkyWatcher EQ6-R.
Polar aligning: QHYCCD PoleMaster.
Field flattener: yes. Filter: no .

Image © R.Powell


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