Irregular variable

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.

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