Program: GN-2010B-Q-13

There is convincing evidence that the progenitors of some SNe Ia have finally been identified. The subset of "super-Chandra" SNe Ia almost certainly result from the merger of two white dwarfs. These SNe show unburned carbon (i.e. progenitor material) in their outer layers, visible only at early times. Other SNe also show this, and thus might be related, but still others show high velocity CaII and SiII at early times instead. High velocity material has been shown to be related to shells or disks or progenitor material causing overdensities in the SN ejecta. Until now, observing SNe Ia early enough to see this -- within a day or two of explosion -- was an extreme rarity. Now the Palomar Transient Factory is making it commonplace. We plan to take the first census of progenitor material in SNe Ia and test whether Hubble diagram residuals from SNe in different environments are correlated with progenitor signatures. Recent advances in observations and theory may finally allow us to test whether SNe arise from the single-degenerate, double-degenerate, or sub-Chandra scenarios. Finally, these GMOS spectra will be used to trigger our Cycle 18 HST STIS program studying early progenitor and metallicity signatures in the UV.