Location of the low-surface-brightness galaxy CDG-2

The low-surface-brightness galaxy CDG-2, shown in this image from the NASA/ESA Hubble Space Telescope, is dominated by dark matter and contains only a sparse scattering of stars. This galaxy is nearly invisible, but by using advanced statistical techniques, scientists identified it by searching for tight groupings of stars called globular clusters. At left, the white box marks the area that was examined. The pullout shown is a magnified view of that area. The circle marked with a dashed red boundary indicates the location of the dark-matter dominated galaxy. Within the dashed circle are four globular clusters outlined by small, blue circles. Several background galaxies also appear within the red circle, but these are not related to the galaxy CDG-2.