ing ▁bin aries . ▁ ▁Properties ▁ ▁Th ub an ▁has ▁a ▁spectral ▁class ▁of ▁A 0 III , ▁indicating ▁its ▁similarity ▁to ▁V ega ▁in ▁temperature ▁and ▁spectrum , ▁but ▁more ▁l umin ous ▁and ▁more ▁massive . ▁It ▁has ▁been ▁used ▁as ▁an ▁M K ▁spectral ▁standard ▁for ▁the ▁A 0 III ▁type . ▁ ▁Th ub an ▁is ▁not ▁a ▁main ▁sequence ▁star ; ▁it ▁has ▁now ▁ceased ▁hydro gen ▁fusion ▁in ▁its ▁core . ▁That ▁makes ▁it ▁a ▁white ▁giant ▁star , ▁being ▁ 1 2 0 ▁times ▁more ▁l umin ous ▁than ▁the ▁Sun . ▁It ▁is ▁ 3 0 0 ▁light ▁years ▁away ▁and ▁its ▁bright ness ▁is ▁only ▁decre ased ▁by ▁ 0 . 0 0 3 ▁magn itudes ▁by ▁interven ing ▁gas ▁and ▁dust . ▁ ▁Popular ▁culture ▁The ▁United ▁States ▁Navy ▁ship ▁ ▁was ▁built ▁in ▁ 1 9 4 3 ▁and ▁de comm ission ed ▁in ▁ 1 9 6 7 . ▁ ▁Th ub an ▁has ▁featured ▁in ▁works ▁of ▁fiction . ▁ ▁References ▁ ▁External ▁links ▁ ▁Jim ▁Kal er ' s ▁Stars , ▁University ▁of ▁Illinois : ▁TH UB AN ▁( Alpha ▁Dra con is ) ▁NASA ' s : ▁History ▁of ▁Pre cess ion ▁: ▁Pre cess ion ▁of ▁the ▁Equ ino xes ▁▁ 1 2 3 2 9 9 ▁ 0 6 8 7 5 6 ▁ 5 2 9 1 ▁Dra con is , ▁Al pha ▁Dra con is , ▁ 1 1 ▁Category : D rac