A dwarf spiral galaxy (D564-15 in the constellation Cancer) shown to the same scale as a giant spiral galaxy (NGC 536 in the constellation Andromeda). The dwarf is in the box at the upper right. Dwarf spiral galaxies are as small as other types of dwarf galaxies, but have the same pinwheel shape and spiral arms found in giant spiral galaxies like the Milky Way.
The diameter of NGC 536 is 54 kiloparsecs (178,000 light-years), while the diameter of D564-15 is only 6.6 kpc (21,500 light-years). Notice that both galaxies have a similar structure: a bright central bulge surrounded by a fainter disk.
D564-15 is one of about six dwarf spirals recently identified during a larger survey of about 110 dwarf galaxies by James Schombert, NASA; Rachel Pildis, University of Michigan; Jo Ann Eder, Arecibo Observatory; and Augustus Oemler, Jr., Yale University.)
Both images were made with the 2.4-meter Hiltner Telescope at Michigan-Dartmouth-M.I.T. Observatory on Kitt Peak, Ariz. The images were presented at the American Astronomical Society Meeting in Tucson, Ariz. on Jan. 10, 1995.