Deneb
Star
Deneb — the blue-white supergiant at the tail of Cygnus the Swan and a corner of the Summer Triangle: one of the most luminous stars known, perhaps 100,000 or more times the Sun's output. Its distance is very uncertain — somewhere from about 1,500 to 2,600 light-years — which is precisely why its true luminosity is so hard to pin down.
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Key facts
Mass
3.78 × 10³¹ kg
19 M☉
Radius
0.93 AU
200× wider than the Sun
Surface temperature
8,525 K (8252 °C)
Luminosity
7.50 × 10³¹ W
Spectral type
A2 Ia (blue-white supergiant)
Science
Physical
- Mass
- 3.78 × 10³¹ kg · 19 M☉
- Radius
- 0.93 AU · 200× wider than the Sun
- Density
- 0.00335 kg/m³ · 3.3e-06× water
- Spectral type
- A2 Ia (blue-white supergiant)
Composition
- By mass
- A blue-white supergiant of extreme luminosity — perhaps ~200,000 times the Sun's — losing mass in a strong stellar wind and the prototype of the Alpha Cygni class of pulsating variables. Its distance is poorly constrained (parallax is very hard for such a remote, luminous star), so its luminosity carries a correspondingly large uncertainty — the quoted value is indicative.
Temperature
- Surface
- 8,525 K (8252 °C)
Radiation & temperature
- Surface temperature
- 8,525 K (8252 °C)
- Peak wavelength
- 340 nm · ultraviolet (invisible to the eye)
Discovery & history
- Method
- Naked-eye star
- Name
- 'Deneb' — from Arabic dhanab, the tail (of the swan); Alpha Cygni.
A fixture of northern summer skies since antiquity as the Swan's tail. Its enormous, poorly-measured distance makes it a benchmark — and a caution — for how hard it is to gauge parallax to the most luminous, most remote naked-eye stars.
Images
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