Dwarf irregular galaxy

Types

• A dI-galaxy (or dIrr) is a dwarf irregular galaxy. Irregular galaxies with luminosities below ${\displaystyle 10^{8}L_{\odot }}$ fall into the dwarf irregular galaxy category. This type of galaxy is now thought to be important to understand the overall evolution of galaxies, as they tend to have a low level of metallicity and relatively high levels of gas, and are thought to be similar to the earliest galaxies that populated the Universe. They may represent a local (and therefore more recent) version of the faint blue galaxies known to exist in deep field galaxy surveys. These types of irregular galaxies also have high amounts of dark matter.