This project seeks a better understanding of the effects of the underlying stellar population on the formation, evolution, and physical properties of binary systems in general and novae in particular. Towards this end, an observational program will be undertaken to study the spatial distributions and outburst properties of novae in nearby galaxies. While stellar population models predict that the disk components of late-type galaxies should produce more novae than spiral bulges and early type-galaxies (as the disks contain a younger population), observational evidence suggests an equal if not greater novae rate among bulges and elliptical galaxies. If confirmed, these results would be indicative of a failure of population synthesis models as well as a problem with the currently favored model for Type Ia supernovae in which accretion onto massive white dwarfs triggers a thermonuclear runaway - Type Ia supernovae are observed to be more common in disks, i.e., the reverse of what may be true for novae.
The observational efforts will be focused along three strategies. First, the true bulge-to-disk ratio of novae in the spiral galaxy M31 and the overall novae rate in the late-type spiral M101 will be determined over the entire spatial extent of the galaxies using the wide field imager on the Steward 90-inch reflector. Second, the maximum brightness and rate of decline of the M31 novae (both in the disk and bulge) will be compared to determine if a radial gradient in speed class exists which would imply two types of novae with properties related to the underlying stellar populations. The necessary light curves will be obtained from follow-up observations at the Mount Laguna Observatory of novae discovered in the wide-field search plus photometry from the Lick Observatory Supernova Search M31 archive and the Robotic Optical Transit Search Experiments. Third, the possibility that the high nova rates for the M13 bulge and M87 (a giant elliptical) are due to nova binaries being generated in globular clusters will be tested by a comparison of nova rates in M49 and M87 - two giant Virgo elliptical galaxies with very different globular cluster populations.
The work here is of the relevance to a broad range of astronomy topics - from binary formation to the origins of Type Ia supernovae. Students from the SDSU REU summer program will be directly involved in the work which includes an exciting "discovery" component. Specific tasks include the discovery of novae and measuring the evolution of their optical light curves. SDSU has a large and diverse student population and this project will enhance the research opportunities available to them.
