What is an irregular galaxy?
Q: What is an irregular galaxy?
A: An irregular galaxy is a type of galaxy that does not have a distinct regular shape, like a spiral or an elliptical galaxy. It does not fall into any of the regular types of the Hubble sequence and usually contains abundant amounts of gas and dust.
Q: How common are irregular galaxies?
A: Irregular galaxies are quite common and may make up around a quarter of all galaxies.
Q: What are the three sorts of irregular galaxies?
A: The three sorts of irregular galaxies are Irr-I, Irr-II, and Dwarf Irregulars.
Q: What is an Irr-I galaxy?
A: An Irr-I galaxy is an irregular galaxy that features some structure but not enough to place it cleanly into the Hubble sequence. Some may be small spiral galaxies being distorted by the gravity of a larger neighbour.
Q: What is an Irr-II Galaxy?
A: An Irr-II Galaxy is an irregular galaxy that does not appear to feature any structure that can place it into the Hubble sequence.
Q: What makes Dwarf Irregulars special? A: Dwarf Irregulars often have a low level of metallicity and relatively high levels of gas which is similar to the earliest galaxies in the Universe. They may be a local (and recent) version of faint blue galaxies known to exist in deep field surveys.
Q: Were Magellanic Cloud Galaxies once classified as irregulars? A: Yes, Magellanic Cloud Galaxies were once classified as irregulars but have since been found to contain barred spiral structures.
