A team of astronomers has accidentally discovered a galaxy that they believe should not exist. The galaxy is so small and ‘alone’ that it does not fit into our current knowledge of galaxies.
The PEARLSDG galaxy was actually found by chance when scientists examined images from the James Webb telescope. They came across a very faint light phenomenon that could not be explained at first, they write in the latest issue of Astrophysical Journal Letters.
Dwarf galaxies contain relatively few stars, fewer than 100 million. That is why they emit little light and are difficult to find for telescopes. For comparison, the Milky Way contains about 200 billion stars.
PEARLSDG is unusually small and dull even for a dwarf galaxy. That indicates that it is already an old galaxy. It is also not located near other galaxies and does not create new stars. Even the smallest galaxies normally do that.
The scientists cannot explain how such a small, quiet and isolated galaxy could have existed for so long. “These types of dwarf galaxies don’t fit with our current knowledge of how galaxies form,” said lead researcher Tim Carleton.
Because PEARLSDG contains a few bright stars, astronomers were able to calculate that the system is located about 98 million light-years from Earth.