An irregular variable is a type of variable star in which variations in brightness show no regular periodicity.
There are two main sub-types of irregular variable: eruptive and pulsating.
Eruptive irregular variables are divided into three categories: Pulsating irregular giants or supergiants, called slow irregular variables, are all of late spectral types (K, M, C, or S), and classed as type L-LB for giants and LC for supergiants.
How many of these are actually semi-regular variables that simply need more study, remains unclear.
This variable star–related article is a stub.