David J. Westpfahl
The VLA is being used to study the neutral hydrogen in the interstellar media of several nearby galaxies to document this evolution. Similar observations are being made of the ionized hydrogen and of the CO molecule using the optical and radio telescopes at Kitt Peak.
These observations have shown the role of companion galaxies in driving spiral structure, the role of vorticity in the evolution of galaxy rotation, and the role of supernovae in determining the size and shape of dwarf galaxies.
(pictured: The neutral hydrogen of M81)