 Like all Cepheid variables, Type IIs exhibit a relationship between the star's luminosity and pulsation period, making them useful as standard candles for establishing distances where little other data is available

Longer period Type II Cepheids, which are more luminous, have been detected beyond the Local Group in the galaxies NGC 5128 and NGC 4258.Historically Type II Cepheids were called W Virginis variables, but are now divided into three subclasses based on the length of their period.Stars with periods between 1 and 4 days are of the BL Herculis subclass and 10–20 days belong to the W Virginis subclass.