SIMBAD references

We explore the idea that the observed variations in the peak luminosities of Type Ia supernovae (SNe Ia) originate in part from a scatter in metallicity of the main-sequence stars that become white dwarfs. Previous numerical studies have not self-consistently explored metallicities greater than solar. One-dimensional Chandrasekhar mass models of SNe Ia produce most of their ⁵⁶Ni in a burn to nuclear statistical equilibrium between the mass shells 0.2 and 0.8 M_☉, for which the electron-to-nucleon ratio Y_eis constant during the burn. We show analytically that under these conditions, charge and mass conservation constrain the mass of ⁵⁶Ni produced to depend linearly on the original metallicity of the white dwarf progenitor. Detailed postprocessing of W7-like models confirms this linear dependence. The effect that we have identified is most evident at metallicities larger than solar and is in agreement with previous self-consistent calculations over the metallicity range common to both calculations. The observed scatter in the metallicity ((1)/(3)-3 Z_☉) of the solar neighborhood is enough to induce a 25% variation in the mass of ⁵⁶Ni ejected by SNe Ia. This is sufficient to vary the peak V-band brightness by|ΔM_V|~0.2. This scatter in metallicity is present out to the limiting redshifts of current observations (z≲1). Sedimentation of ²²Ne can possibly amplify the variation in ⁵⁶Ni mass to ≲50%. Further numerical studies can determine if other metallicity-induced effects, such as a change in the mass of the ⁵⁶Ni-producing region, offset or enhance the variation that we identify.