Type II Cepheids - W Vir and BL Her variables - 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 F-G III-Ib. Their periods range from 0.8 to 35 days, and amplitudes from 0.3 to 1.2 mag in V. They follow a Period-Luminosity relation, but different than that of the Cepheids. Corresponding types in the GCVS are : CW, CWA (W Vir), CWB (BL Her).

-- CecileLoup - 2014-04-08