Alpha Draconis


Distance (Light Years) 309 ± 15
Apparent Magnitude 3.67
Color (B-V)-0.05

Names For This Star

One of the Arab names for the constellation of Draco was Al Thuban, which according to Allen is an Arab translation of "Draco," that is, a dragon. The Arabic name of the constellation has come to be attached to the star.

Another name for the star is Adib from the Arabic Al Dhi'bah, "The Hyenas". A number of stars in Draco, Boötes, and Ursa Major were considered to be among the hyenas.

According to Allen, seamen were accustomed to call Thuban "The Dragon's Tail."

Description of the Star

Thuban is a white A0III giant having a luminosity about 260 times that of the sun. Spectral analysis indicates that Thuban has a companion star orbiting with a 51.4 day period. Burnham gives the separation between the stars as about 20 million miles.

Other Designations For This Star


11 Draconis

Hipparcos Identifier (HIP Number)


Harvard Revised (HR Number)


Henry Draper Catalog (HD Number)


Bonner Durchmusterung (BD Number)

BD+65 978
Smithsonian Astrophysical
Observatory compendium (SAO Number)

Fundamental Katalog (FK5 Number)



Copyright © 1998 - 2010 by Arnold V. Lesikar,
Professor Emeritus
Dept. of Physics, Astronomy, and Engineering Science,
St. Cloud State University,St. Cloud, MN 56301-4498

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