· · · ·


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

Proper NamesDeneb, Deneb Cygni, Arided, Aridif
Bayer DesignationAlpha Cygni
Flamsteed Number50 Cygni
HR (BSC)7924
Right Ascension20h 41m 26s
Declination+45° 16' 49"
Distancec.2,600 light years
c.800 parsecs
MagnitudeApparent: +1.3
Absolute: +6.9
Spectral ClassA2Ia White Supergiant
Optimum VisibilityAugust (Usually visible from northern latitudes)
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 shines against the backdrop of a broad field of nebulosity. Notable in this image are two named nebulae to the east (left) of the star: the North America Nebula (NGC 7000) and, separated from it by a dark lane of material, the Pelican Nebula (IC 5070). Imagery provided by Aladin sky atlas

* 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.


Related Entries