RR Lyrae are pulsating variable stars on the Horizontal Branch in the instability strip. Their initial mass is about 0.5 Mo, and they belong to population II. Their spectral type are A-F III. Their periods range from 0.2 to 1.2 days, and amplitudes from 0.2 to 2 mag in V. Corresponding types in the GCVS are : RR, RR(B), RRAB, RRC.

-- CecileLoup - 2014-04-08