The term 'long-period variable' is usually taken to be another name for a Mira variable. There is no Cepheid-type period-luminosity law and indeed the periods and the amplitudes are not constant. In the past, the term was applied more generally to mean any red giant or supergiant pulsating variable with a period of 20 to 1,000 days, including, in addition to Mira variables, semi-regular variables and slow irregular variables. Long-period blue variables are pulsating B stars with periods longer than one day and amplitudes generally less than 0.05 magnitude but occasionally up to 0.1 magnitude.

 

S Vulpeculae star

An S Vulpeculae star is a type of long-period variable consisting of a yellow giant or supergiant that behaves like a Cepheid variable most of the time but occasionally goes through phases when it becomes erratic and unpredictable. S Vulpeculae itself has a period of 68.5 days.