Gamma Draconis
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| Observation data Epoch J2000 |
|
|---|---|
| Constellation | Draco |
| Right ascension | 17h 56m 36.4s |
| Declination | +51° 29′ 20.3″ |
| Apparent magnitude (V) | 2.24 |
| Characteristics | |
| Spectral type | K5 III |
| B-V color index | 1.52 |
| U-B color index | 1.87 |
| Variable type | ? |
| Astrometry | |
| Radial velocity (Rv) | -28 km/s |
| Proper motion (μ) | RA: -8.52 mas/yr Dec.: -23.05 mas/yr |
| Parallax (π) | 22.10 ± 0.46 mas |
| Distance | 148 ± 3 ly (45.2 ± 0.9 pc) |
| Absolute magnitude (MV) | -1.04 |
| Details | |
| Mass | 1.7 M☉ |
| Radius | 50 R☉ |
| Luminosity | 600 L☉ |
| Temperature | 4,000 K |
| Metallicity | ? |
| Rotation | <17 km/s. |
| Age | ? years |
| Other designations | |
Gamma Draconis (γ Dra / γ Draconis) is a star in the constellation Draco. It also has the traditional name Eltanin, also Etamin.
It is an orange giant of spectral type K5. Despite its Bayer designation of "gamma", it is actually the brightest star in Draco, outshining Rastaban (Beta Draconis) by nearly half a magnitude. In fact, the name Rastaban (also Rasaben) was formerly used for Eltanin, and the two terms share an Arabic root meaning "serpent" or "dragon." Because of its proximity to the point directly overhead London, it has also been called Zenith Star.
In 1728, while unsuccessfully attempting to measure the parallax of this star, James Bradley discovered the aberration of light resulting from the movement of the Earth.
[edit] See also
[edit] References
Kaler, Jim (2004). "STARS: Eltanin". Retrieved July 11, 2005.
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