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Deneb
Alpha (α) Cygni
Blue Star
| Right Ascension | 20h 41m 26s | Best Seen | 7/1 - 12/15 |
| Declination | 45° 16' 49" | Magnitude | 1.25 |
| Constellation | Cygnus | ||
Actual |
Compared to Sun |
|
| Distance | ~3,230 ly | -- |
| Actual Brightness | -- | 80,000 |
| Surface Temperature | ~18,000 ºF | ~1.8 |
| Diameter (average) | ~147 million miles | 170 |
| Mass | -- | -- |
| Surface Gravity | -- | -- |
| Surface Composition (by mass) | 74% hydrogen 24% helium 2% everything else |
same |
| Spectral Type | A2 lae | G2 V |
| Density (gram/cubic cm) | -- | -- |
What To Look For Through The Telescope
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Recommended eyepiece: 24mm or 40 mm.
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When people look through the telescope a bright bluish point of light should be seen.
Deneb Information:
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Deneb is the 14th brightest star in the Northern Hemisphere’s night sky (19th brightest in the night sky when including Southern Hemisphere’s bright stars).
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Deneb radiates nearly 80,000 times as much energy as our sun does!
Yet because it is so very far away, it’s not very bright in the sky.
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References
| Item | Updated | Notes |
| Coordinates | 2002-07-15 | SIMBAD |
| Distance | 2002-07-15 | from 1,600 ly to 3,230 ly (Hipparcos) |
| Actual Brightness | 2002-10-18 | see the addendum to Scott’s The Flamsteed Collection |
| Surface Temperature | 2002-07-15 | with approx. temp. 10,000K for A stars |
| Diameter | 2002-07-15 | with approx. temp. 10,000K for A stars; and luminosity 244,000 times the sun |
| Mass | 2002-07-15 | previously said 25 times that of sun |
| Surface Gravity | -- | -- |
| Surface Composition | 2003-01-06 | OK for all stars |
| Spectral Type | 2002-07-15 | from A2 Ia to A2 Iae (SIMBAD) |
| Other Information | 2002-07-22 | 1. added #2. why Deneb not so bright 2. with Hipparcos, brightness “rank” |
| Composition | 2013-07-30 | Changed to 74% / 24% / 2% |