Deneb
 Cygnus, the constellation in which Deneb is located. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 20h 41m 25.9s |
| Declination | +45° 16' 49" |
| Apparent magnitude (V) | 1.25 |
| Characteristics | |
| Spectral type | A2 Ia |
| U−B color index | −0.24 |
| B−V color index | +0.09 |
| Variable type | Alpha Cyg |
| Astrometry | |
| Radial velocity (Rv) | −4.5 km/s |
| Proper motion (μ) | RA: 1.56 mas/yr Dec.: 1.55 mas/yr |
| Parallax (π) | 1.01 ± 0.57 mas |
| Distance | 3229 ly (990 pc) |
| Absolute magnitude (MV) | −8.73 |
| Other designations | |
Deneb (α Cyg / α Cygni / Alpha Cygni) is the brightest star in the constellation Cygnus and one of the brightest stars in the night sky, with apparent magnitude 1.25.
It is, or has been, known by a number of other traditional names, including Arided, Aridif, but today these are almost entirely forgotten.
Distance and physical characteristics
Deneb's absolute magnitude is −8.73, placing it among the most luminous stars known.
Deneb's exact distance from the Earth is a matter of some dispute; figures from 1600 to 3200 light years appear on various online sources. It should be noted that determination of distances at this range is very difficult because stars with such distances have negligible parallax. Moreover, the uncertainty about distance makes determining its other properties similarly imprecise.
Estimates for Deneb's luminosity range from about 60,000 times the brightness of our Sun (if Deneb is 1600 light years away) to 250,000 times the Sun's brightness (if 3200 light years away). If Deneb were a point source of light at the Sun's distance from Earth, it would be far brighter than most industrial lasers—It generates more light in one day than the Sun does in 140 years. At the distance of Sirius, it would be brighter than a full moon.
Based on its temperature and luminosity and also on direct measurements of its tiny angular diameter (a mere 0.002 second of arc), Deneb appears to have a diameter about 200 to 300 times that of the Sun; if placed at the center of our Solar System, Deneb would extend to the orbit of the Earth. It is one of the largest stars known and the most powerful class A star known.
A star of spectral type A2Ia, Deneb has a surface temperature of 8,400 kelvins. Deneb is the prototype of a class of variable stars known as Alpha Cygni variables. Its surface undergoes non-radial fluctuations, which cause its brightness and spectral type to change slightly.
Deneb's mass is estimated at 20 to 25 solar masses. As a blue giant, its high mass and temperature mean that the star will have a short lifespan and will probably become a supernova within a few million years. It has already stopped fusing hydrogen in its core.
Deneb's solar wind causes it to lose mass at a rate of 0.8 millionth of a solar mass per year, a hundred thousand times the flow rate from the Sun.
Name
The name is from dheneb, the Arabic for "tail", from the phrase ذنب الدجاجة <eth>anab ad-dajājah, or "tail of the hen". Similar names were given to at least seven different stars, most notably Deneb Kaitos, the brightest star in the constellation Cetus, and Denebola, the second brightest star in Leo.
Mythology
In the Chinese love story of Qi Xi, Deneb marks the magpie bridge across the Milky Way which allows the separated lovers Niu Lang (Altair) and Zhi Nü (Vega) to be reunited on one special night of the year in late summer. In other versions of the story Deneb is a fairy who acts as chaperone when the lovers meet across the bridge of magpies.
Deneb in fiction
- In the Star Trek: The Original Series episode "Where No Man Has Gone Before", Captain Kirk and Gary Mitchell briefly mention a night Mitchell spent on Deneb IV. Mitchell describes the Denebian woman involved as "a nova". Mitchell's medical record mentions that the inhabitants of Deneb IV are telepathic.
- In the Star Trek: The Original Series episode "The Trouble With Tribbles", Korax describes Captain Kirk as being a Denebian slime devil.
- Deneb IV is also mentioned in the Star Trek: The Next Generation episode "Encounter at Farpoint".
- Deneb is also the name of the witch from Zenobia in the Ogre Battle video game series. She is a magical alchemist of sorts, using her arcane knowledge and power to create the demihuman race of Pumpkinheads. She has the distinction of being the only character to appear in every Ogre Battle title to date. She is one of many characters in the game who is named after a star.
- Deneb is the home of Jeff Raven in the Talents series of books (The Rowen, Damia, Damia's Children, Lyon's Pride, The Tower and The Hive) by Anne McCaffrey. The planet is the first human planet in the series to be attached by the bug-like Hive.
- Deneb is also the location of a major battle in the computer game Freespace 2 between the Galactic Terran Vasudan Alliance and the Neo-Terran Front during the late 24th century.