查看“BHB stars”的源代码

A kind of Population II star, found in the  galactic halo and especially in globular clusters, that has evolved past the red   giant stage and is now burning helium  in its core. Blue horizontal-branch (BHB) stars are typically of spectral       type B3 to A0 (hence very blue in color), and have spectra characterized by strong, sharp hydrogen lines, a large Balmer, and very weak lines of other elements. 
      
BHB stars are found on the horizontal  branch of the Hertzsprung-Russell diagram  to the left, blue side of RR Lyrae variables.  They are very good tracers because of their extreme brightness and the fact  that most faint blue stars seen in the halo are usually BHB stars.