2007/02/08 by P. A. Mazzali, F. K. Roepke, F. K. Röpke +2 · 8 citations
Physics and Astronomy · #Astro and Planetary Science #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1126/science.1136259
published as Science315:825,2007 · 8 pages, 2 figures
openalex publication_date 2007/02/08 · arxiv created 2007/02/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Type Ia supernovae, the thermonuclear explosions of white dwarf stars composed of carbon and oxygen, were instrumental as distance indicators in establishing the acceleration of the universe's expansion. However, the physics of the explosion are debated. Here we report a systematic spectral analysis of a large sample of well-observed type Ia supernovae. Mapping the velocity distribution of the main products of nuclear burning, we constrain theoretical scenarios. We find that all supernovae have low-velocity cores of stable iron-group elements. Outside this core, nickel-56 dominates the supernova ejecta. The outer extent of the iron-group material depends on the amount of nickel-56 and coincides with the inner extent of silicon, the principal product of incomplete burning. The outer extent of the bulk of silicon is similar in all supernovae, having an expansion velocity of approximately 11,000 kilometers per second and corresponding to a mass of slightly over one solar mass. This indicates that all the supernovae considered here burned similar masses and suggests that their progenitors had the same mass. Synthetic light-curve parameters and three-dimensional explosion simulations support this interpretation. A single explosion scenario, possibly a delayed detonation, may thus explain most type Ia supernovae.