Hubble Space Telescope detection of spiral structure in two coma cluster dwarf galaxies

We report the discovery of spiral-like structure in Hubble Space Telescope images of two dwarf galaxies (GMP 3292 and GMP 3629) belonging to the Coma Cluster. GMP 3629 is the faintest such galaxy detected in a cluster environment, and it is the first such galaxy observed in the dense Coma Cluster. The large bulge and the faintness of the broad spiral-like pattern in GMP 3629 suggest that its disk may have been largely depleted. We may therefore have found an example of the missing link in theories of galaxy evolution that have predicted that dwarf spiral galaxies, particularly in clusters, evolve into dwarf elliptical galaxies.