One of the most peculiar of galaxies, I Zwicky 18 has been for some time thought to be a close resemblance to early galaxies.

The galaxy has very poor metallicity, meaning most of the stars are being born from hydrogen and helium, with little other element involved.

This is peculiar because the galaxy also shows huge star formation, and stars fuse hydrogen and helium into metals, and so it was assumed this galaxy itself must be incredibly young, just a few million years old.

That was until Hubble started looking at it a decade or more ago, and found stars of all types, G, K and M types with ages most likely in their billions, if not right back to the start of the universe itself.

So, how did this galaxy avoid star formation for so long, it's a bit of a mystery. We know JWST has since discovered galaxies in the early universe were not anything like what we imagined, and while that may reduce some interest in I Zwicky 18, the mysteries of it's creation and history will certainly keep astronomers focused on this.

The galaxy also has companions, which also seem to follow the same bizarre construction.

NGC 6822 - Barnard's Galaxy

E.E Barnard was is probably the only astronomer to have a star and a galaxy named after him, as well as a whole area of nebula called Barnard's loop.

The galaxy is very close at 1.63 million light years, but probably not so well known because it's an irregular dwarf galaxy, similar to the Small Magellanic Cloud, and sadly such galaxies don't get the kind of interest than more beautiful spirals or dramatic lenticular and ellipses do.

Yet, a quick look and you'll spot supernova remnants abound, those red bubbles which now are areas of intense nebula created by the shockwave as it pushes and clears the space around the supernova, but increases the density sufficiently at the outer edges to create stars.

Above an image of an area known as Hubble V, named after the telescope that took the image, shows the large cluster of stars, huge area of nebula that both created those stars, and is fed by those stars when they go supernova.

And of course, JWST has also taken a look, and despite being just 7,000 light years across (our Milky Way being 100,000), the density of stars and star forming regions make this galaxy spectacularly interesting, both to view and to study.

NGC 2814 - Irregular Galaxy

Not all galaxies fit the classical shapes of spiral, elliptical or lenticular, some appear to have no obvious form, and these are classified as irregular. Many have found there way to this state through interaction with other galaxies, while others we can only speculate to how they came to be as they are.

This recent Hubble image shows NGC 2814 which is 84 million light years from us in the constellation of Ursa Major, and a close companion to a number of other galaxies which make up the Holmberg 124 group.

Hubble Homes in on ESO 300-16

Not all galaxies are spiral, ellipse or lenticular, many smaller galaxies have no obvious morphology, and therefore fall into the category of irregular galaxies.

ESO 300-16 lies 28.7 million light years from Earth in the constellation of Eridanus and has been described has having a ghostly faint glow.

It's part of a study being carried out by Hubble to get images of most of the nearby galaxy objects, many of which are dwarf irregular galaxies such as this.

Astronomers are interested in such galaxies because they give hints at the forces which go about creating galaxies, and ultimately what ends them. They will be looking at the chemical make up such as metallicity, the number of globular clusters, rate of star birth and if the galaxy has a supermassive black hole, and the way it moves through space and possibly interacts with dark matter.

Barnard's Galaxy NGC 6822

Not all galaxies are beautiful spiral patterns, Barnard's galaxy, a mere 1.6 million light years from Earth and part of the local group of galaxies is a dwarf irregular galaxy, not too dissimilar to the Large Magellanic Clouds that orbit our own galaxy.

The galaxy is made up of numerous massive blue young stars, and still shows large nebulous regions (in pink) where the process of star formation is still very much an active event.

Barnard’s Galaxy, NGC 6822

Not all galaxies are Spiral, lenticular or elliptical, many small galaxies (often called dwarf galaxies) have no obvious shape, and are referred to as irregular galaxies.

Andromeda spiral galaxy may be the closest large spiral galaxy, but it’s not the closest. The Magallanic clouds that orbit our galaxy are indeed the closest, but around 1.6 million light years from us lies Barnard’s Galaxy, the closest non-gravitationally bound galaxy to us.

Dwarf galaxies outnumber the larger spiral galaxies, and often end up as snacks, in fact, several have merged in with the Milky Way over the last 10 Billion Years, sometimes significantly adding to our galaxy.

NGC 5477 Dwarf Galaxy

Most dwarf galaxies are irregular in shape and orbit much larger galaxies (although not always). This galaxy is part of the M101 group, just over 20 million light years from Earth in the constellation of Ursa Major. Despite it’s size, it certainly isn’t holding back on star birth. The blue regions in the image show regions of hydrogen gas illuminated by new O and B type stars (which hold a slightly blue hue). Even our own Magellanic clouds that orbit our galaxy have some of the most spectacular star forming regions. 

While dwarf galaxies are thought to contain much smaller supermassive blackholes, one difference is, that in some studies, it was found that unlike in more massive galaxies, half of the dwarf galaxies were showing supermassive black holes not in the centre of the galaxy, but rather out towards the edges. 

NGC 14

Not all Galaxies are spiral or globular in nature, almost a quarter of all galaxies have no easy definable pattern, and are known as irregular galaxies. 

Many of these irregular galaxies contain part of a spiral arm, or a bulge, and probably indicate a collision or gravitational tear apart that has disrupted it’s previous pattern.