Dr. Allen Shafter will continue his study of the spatial distributions, populations, and outburst properties of novae in selected nearby galaxies. The principal motivation of the study is to acquire a deeper understanding of the effect that the underlying stellar population has on the formation, evolution, and physical properties of close binary systems in general, and novae in particular. Novae are ideally suited to this task because they have high luminosities and can be readily identified in galaxies spanning a wide range of types.
Models based on standard nova formation scenarios predict that the disk components of late-type galaxies with their young stellar population component should be more prolific nova producers (i.e., they should have more nova eruptions per unit mass in stars) compared with spiral bulges and early-type galaxies. The available observational evidence, however, seems in conflict with this prediction, with the bulges of spirals and elliptical galaxies appearing to have nova rates as high, or higher, than that seen in younger stellar populations. If confirmed, these results create a problem not only for stellar population models, but for the currently favored model for the progenitors of Type Ia supernovae which are used to determine the expansion rate of the universe.
The results of the study will be relevant to a wide range of topics in astronomy, from the formation and evolution of close binary stars such as novae, to their potential role as a progenitor channel for Type Ia supernovae. Students from San Diego State University (SDSU), and from SDSU's Research Experience for Undergraduates (REU) summer program, will be directly involved in the discovery of these novae, in measuring their spectra, and in determining the evolution of their optical light.
