Mergers between these objects can be classified as wet or dry depending on their gas richness.
Mergers between these objects can be classified as wet or dry depending on their gas richness. Modified Newtonian Dynamics can be used to explain their namesake rotation problem. Hoag's Object is an example of the ring type of them, and they can be organized into groups, clusters, and superclusters. These astronomical objects are classified on a tuning-fork diagram devised by Edwin Hubble, who also names a law stating the distance between them is increasing. For 10 points, name these systems of dust, gas, and stars that can have elliptical or spiral shapes.
Mergers between these objects can be classified as wet or dry depending on their gas richness.
galaxies [or galaxy]