White dwarfs are dead stars that have the approximate mass of the Sun, but size of the Earth. They are made up of extremely densely packed carbon and oxygen atoms. A Type Ia supernova occurs when a white dwarf in a binary star system pulls enough mass from its partner to trigger an explosion. When helium is the type of mass transferred from the donor star, this is called a Type Iax. Type Iax supernovae appear weaker than Type Ia and they may leave behind a surviving white dwarf. This project will use spectra of several Type Iax supernovae to test models of how both types are formed. Since Type 1a supernovae are often used as distance indicators, results from this work will help test models of the expanding universe. A graduate student and postdoctoral researcher will be trained and mentored in research. The team will also prepare and distribute physics education materials aimed at preparing under-represented students for graduate school. This project will test the hypothesis that Type Ia explosions arise from double-degenerate progenitors, while SN Iax come from single-degenerate systems by analyzing spectra of early-phase and late-phase Type Iax supernovae. The researchers will use data from existing Pan-STARRS and ASASSN (All-Sky Automated Survey for Supernovae) surveys and collect new data from the SALT (Southern African Large Telescope) and Gemini Observatory instruments. The project includes a detailed comparison between the spectra and model predictions to constrain elemental composition and velocities. The team will also apply these techniques to other classes of unusual white dwarf supernovae, including those where the inferred ejecta masses are more than 1.4 solar masses.
|Effective start/end date||9/1/16 → 8/31/19|
- National Science Foundation (National Science Foundation (NSF))