Compact groups of galaxies in the nearby universe.

We have searched for compact groups of galaxies among the largest catalog of nearby groups (LGG catalog). 21 new compact groups of at least 3 members were found. Their surface brightnesses are generally lower than those of Hickson compact groups (HCGs), and their characteristics are close to those of loose groups. We have also retrieved all HCGs of the nearby universe. These are all embedded in groups, forming the cores or substructures of loose groups. These results suggest that compact groups may form as cores or substructures within loose groups (like the HCGs), or form from loose groups when they start collapsing (like those of the LGG).