Type Ia Supernovae

Supernovae are some of the brightest and most energetic explosions in the universe. In the mid- to late-twentieth century, it was discovered that Type Ia supernovae, the brightest and most homogeneous subtype, are a different breed from the rest. Observational evidence suggest these explosions are thermonuclear detonations of carbon-oxygen white dwarf stars. The current theory of Type Ia supernovae is discussed here, beginning with a review of the physics of white dwarf stars in context to stellar evolution, composition, properties, and the Chandrasekhar mass limit. The discussion of the explosion itself will include carbon and oxygen ignition, the geometry and composition of the ejecta, and the effects of radioactive decay on late light curves. The nature of the progenitor binary companions of Type Ia supernovae is not well understood, leading to a discussion of theoretical progenitor scenarios and their relative strengths and weaknesses. Type Ia supernovae are powerful distance indicators and excellent probes for cosmic evolution. In the late 1990s, observations of the most distant Type Ia supernovae revealed the accelerated expansion of the universe. For further progress to be made in the field of cosmology, a complete theory of Type Ia supernovae is needed. I will end by discussing what is currently being done by observational astronomers for unveiling the answers to outstanding questions on the nature of these enigmatic phenomena