Encyclopedia Britannica defines a galaxy as “any of the systems of stars and interstellar matter that make up the universe.” This may soon need to change thanks to the discovery of J0613+52 – a galaxy without a single visible star.
Astronomers were using radio telescopes to study a selection of galaxies which have very few stars. Instead, these ‘low surface brightness galaxies’ are mainly made of gas and dark matter. However, when the researchers compared their data, they realised that the Green Bank Telescope had been looking in the wrong place.
Instead of the galaxy they had meant to study, the telescope been pointed at something completely new. The gas making up J0613+52 is very spread-out and hasn’t been disturbed by any nearby galaxies, which means it never collapsed together to form stars (so far as we can tell). Apart from that, it looks like a normal spiral galaxy, perhaps revealing what our own Milky Way looked like when it first formed.
Lachlan Writes Science 