Daily Beast: Earlier this year, 47 galaxies with certain similarities were found in the Coma Cluster. They are all nearly as large as the Milky Way but have only as many stars as dwarf galaxies and almost no gas, which makes them hard to detect. Now, 854 more of these "ultra diffuse galaxies" (UDGs) have been found in the same area, near the heart of the Coma Cluster. Despite the galaxies' low density of stars and gas, their structures are similar to those of normal galaxies, which suggests they have an abundance of dark matter. However, until the galaxies' mass can be measured, that cannot be confirmed. Whether UDGs are present in all galaxy clusters or only in old, large ones like the Coma Cluster is still an open question as well.
