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Deneb

Deneb Cygni, Arided, Aridif, Alpha Cygni, 50 Cygni

Proper NamesDeneb, Deneb Cygni, Arided, Aridif
Bayer DesignationAlpha Cygni
Flamsteed Number50 Cygni
HR (BSC)7924
HD197345
ConstellationCygnus
Right Ascension20h 42m 2s
Declination+45° 20' 41"
Distancec.2,600 light years
c.800 parsecs
MagnitudeApparent: +1.3
Absolute: +6.9
Spectral ClassA2Ia White Supergiant
Optimum VisibilityAugust
NotesA supergiant star with a bluish-white colour, Deneb is noted as being one of the most luminous stars known. It generates at least 50,000 times as much light energy as the Sun, and perhaps a great deal more. With Vega and Altair it forms the great Summer Triangle formation of northern skies.

A gigantic and turbulent star, the brightest in Cygnus and nineteenth brightest in the entire sky, despite being up to 3,000 light years* from the Solar System. If it were just ten parsecs distant, it would shine almost as brightly as the full Moon.


* Deneb's distance from the Sun is not known with certainty, but the figure given here of some 2,600 light years is currently generally accepted, based on various methods of calculation. The star's parallax (the most usual basis of a distance calculation) is 2.31, giving a rather shorter distance of about 1,500 light years, though the fact that Deneb is a pulsating variable means that the parallax method is not considered entirely reliable in this particular case.

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