Thuban
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Thuban (), with Bayer designation Alpha Draconis or α Draconis, is a binary star system in the northern constellation of Draco. A relatively inconspicuous star in the night sky of the Northern Hemisphere, it is historically significant as having been the north pole star from the 4th to 2nd millennium .
Astronomical data · SIMBAD
- Object type
- SB*
- Spectral type
- A0III
- Distance
- 261 light-years
- Redshift
- z = -0.000020347202802750708
- Coordinates
- RA 211.0973° · Dec 64.3759°
via SIMBAD · CDS Strasbourg
Wikidata facts
- Distance from Earth
- 79.9003
- Radius
- 3.4
- Mass
- 2.8
- Image
- Alpha Draconis.jpg
Show 16 more facts
- spectral class
- A0IIISB
- catalog code
- Renson 35350
- apparent magnitude
- 3.652423
- effective temperature
- 10080
- parallax
- 12.5156
- stellar rotational velocity
- 25
- radial velocity
- -14.6
- metallicity
- -0.19
- surface gravity
- 2000
- absolute magnitude
- -1.20
- luminosity
- 300
- right ascension component of proper motion
- -56.351
- declination component of proper motion
- 12.329
- age estimated by a dating method
- 280
- right ascension
- 211.09732332021125
- declination
- 64.3758696175675
via Wikidata · CC0
~5 min read
Article
7 sectionsContents
- Nomenclature
- Visibility
- Pole star
- Binary system
- Properties
- References
- External links
Thuban (), with Bayer designation Alpha Draconis or α Draconis, is a binary star system in the northern constellation of Draco. A relatively inconspicuous star in the night sky of the Northern Hemisphere, it is historically significant as having been the north pole star from the 4th to 2nd millennium .
Johann Bayer gave Thuban the designation Alpha and placed it as the only member of his secundae magnitude class in Draco, although its current apparent magnitude of 3.65 means it is 3.7 times fainter than the brightest star in the constellation, Gamma Draconis (Eltanin), which Bayer placed in his tertiae magnitude class although its current apparent magnitude is 2.24.