Irregular Galaxy Facts
IRREGULAR GALAXY FACTS
The home of interesting irregular galaxy facts for kids and adults.
Interesting facts about irregular galaxies.
What is an irregular galaxy?
Many people know about spiral and elliptical galaxies, but many of those people are not aware of the third type of galaxy – the irregular type – and what it is. It is named irregular because it doesn’t take on a strict form, or shape, in the way the others do.
They are however some of the brightest galaxies in our night sky, and this is because of their abundance of stars. We have here 10 other facts about irregular galaxies that you probably didn’t know.
10 Facts about irregular galaxies you didn't know.
1. Irregular galaxies are among the youngest
Irregular galaxies on average are some of the youngest that live in our observable universe. These types are normally somewhere between 4 billion and 8 billion years old.
Did you know?
The oldest observed galaxy is GN-z11, which is thought to be 40 billion years old.
2. There are lots of examples of irregular galaxies
There are of course lots of examples of all the types of galaxies, and each has their own poster galaxy. In the case of irregular galaxies, a dwarf irregular by the name of IC 4710, in the Pavo constellation, is the more well known.
Did you know?
Irregulars tend to be small, with the average being 20,000 light-years in diameter and dwarf irregulars being around 1,000 light-years in diameter.
3. Irregulars can have bars, just like spirals
Some irregulars can be barred, just like spirals. A near central bar structure dominates an otherwise unstructured, chaotic, collection of cosmic material.
Did you know?
The Large Magellanic Cloud type was thought to be a barred irregular .
4.Irregular galaxies make up around a quarter of all galaxies
It is theorised that some irregulars used to be either elliptical air spiral galaxies but at some point were deformed by external, uneven gravitational force. This ends with them having a chaotic look about them.
Did you know?
Irregulars may have lots of gas and dust, but this is not always true of dwarf irregulars.
5. Magellanic Clouds were thought to be irregular galaxies
Magellanic Clouds have been reclassified as being a type of barred spiral galaxy, otherwise now known as a barred Magellanic spiral type.
Did you know?
The Small Magellanic Cloud is still known as an irregular type, although it contains a bar structure.
6. Irregular galaxies have a small mass
Because irregulars are relatively small for galaxies, they also have small masses (usually around one million times the mass of the sun) it is because of this that they have much fewer stars, relatively speaking.
Did you know?
A galaxy’s mass can be worked out by measuring the orbital speed of the stars and other matter within them.
7. An Irr-I galaxy is the first type of irregular galaxy
There are three types of irregular galaxy, Irr-I is the first. This is an irregular type that has some structure but not enough to take it out of the irregular category.
Did you know?
Some of these types are small and being distorted a larger neighbour’s gravity.
8. An Irr-II is the second type or irregular
This type of irregular galaxy is one that does not appear to have any kind of structural feature at all, at least none that put it in the Hubble Sequence (a galaxy classification system).
Did you know?
The Hubble Sequence was created by Edwin Hubble in 1926.
9. Dwarf Irregulars are the third type of irregular galaxy
This type may be important because they usually have low levels of metallicity and relatively high gas levels. This is similar to the the first galaxies, and they may have a lot to teach us.
Did you know?
Dwarf irregulars could be local, recent, versions of blue galaxies that exist in deep space surveys.
10. Irregulars are formed through gravity and mergers
It seems likely that irregular galaxies are formed by way of gravitational interactions and the merging of other galaxies. The majority of irregulars started life as a different type of galaxy.
Did you know?
Through these mergers and interactions, these galaxies lost a lot of their features and their shape became ‘irregular’.