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Thuban is a rare white giant [[star]] of spectral class A0 III.<ref>http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alpha+Draconis</ref>  The star is much like [[Vega]]. As a giant star, however, Thuban has already evolved off of the main sequence.  The star is 3.5 times the mass of our [[Sun]], and is 265 times the radius.  The star is 300 times as visually luminous as the Sun even though much of the energy emitted is in the [[ultraviolet]].  The surface temperature is 9800 K.<ref name="illinos">http://stars.astro.illinois.edu/sow/thuban.html</ref>  

Thuban is a rare white giant [[star]] of spectral class A0 III.<ref>http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alpha+Draconis</ref>  The star is much like [[Vega]]. As a giant star, however, Thuban has already evolved off of the main sequence.  The star is 3.5 times the mass of our [[Sun]], and is 265 times the radius.  The star is 300 times as visually luminous as the Sun even though much of the energy emitted is in the [[ultraviolet]].  The surface temperature is 9800 K.<ref name="illinos">http://stars.astro.illinois.edu/sow/thuban.html</ref>  

As a giant, Thuban has already used up its core [[hydrogen]] fuel.  Depending on the stage of its life as a giant, the star may be either expanding and cooling to become an orange giant or that the [[helium]] fuel in the core has already been used up.  If the latter is true, the star is actually contracting and will start to fuse [[carbon]] in the core, becoming a blue giant. <ref name="illinos">http://stars.astro.illinois.edu/sow/thuban.html</ref>  

As a giant, Thuban has already used up its core [[hydrogen]] fuel.  Depending on the stage of its life as a giant, the star may be either expanding and cooling to become an orange giant or that the [[helium]] fuel in the core has already been used up.  If the latter is true, the star is actually contracting and will start to fuse [[carbon]] in the core, becoming a blue giant.<ref name="illinos"/>  

It is known that Thuban has a small companion star. The companion, which has not been directly imaged, orbits the primary once every 51 days and may be either a red or [[white dwarf]].<ref name="illinos">http://stars.astro.illinois.edu/sow/thuban.html</ref>  

It is known that Thuban has a small companion star. The companion, which has not been directly imaged, orbits the primary once every 51 days and may be either a red or [[white dwarf]].<ref name="illinos"/>  

==Thuban as a Pole Star==

==Thuban as a Pole Star==