Lowell Observatory

The dwarf irregular galaxy DDO 133.

The Structure of Small Galaxies

Little galaxies pose big questions. Stars form from gas in their parent galaxies, and if the gas is too tenuous, theories predict that no stars should be able to form. But that's not what we see: observations of dwarf galaxies by Lowell astronomer Deidre Hunter and her colleagues show stars forming in regions where no star formation is expected to happen.

What's wrong with the models? Where do galaxies "end," i.e., how and why do stars form at the edges of galaxies, and what defines those edges?

These are key questions with implications for the evolution and structure of not only individual galaxies, but galactic clusters and large-scale structure as well, since giant elliptical galaxies, which dominate their environments and the evolution of the clusters they belong to, are thought to be the product of mergers of these smaller galaxies.

Galaxy research with the DCT will employ both its imaging and spectroscopic capabilities. Wide-field, ultra-deep imaging will allow examination of the distribution of gas and stars in the most tenuous parts of galaxies. Spectroscopy will reveal the motions of the stars and gas in them, providing information about their structure and evolution.