Analysis of the Type Ia Supernova SN1994D

Abstract

We present an analysis of the observed light curves and spectra of the Type Ia supernova SN1994D in the galaxy NGC 4526. The sensitivity of theoretical light curves and spectra to the underlying hydrodynamical model is discussed. The calculations are consistent with respect to the explosion mechanism, the optical and infrared light curves, and the spectral evolution, leaving the description of the nuclear burning front and the structure of the white dwarf as the only free parameters. The explosions are calculated using a one-dimensional Lagrangian code including a nuclear network. Subsequently, the light curves are constructed. Detailed NLTE-spectra are computed for several instants of time using the density, chemical, and luminosity structure resulting from the light curve code. Different scenarios have been compared to the observations including detonations, deflagrations, delayed detonations, tamped detonations and Helium detonations. Only one of our delayed detonations models shows good agreement with the observations of SN1994D both for the B, V, R and I colors and the spectral evolution. The classical deflagration model W7 does not reproduce the high Si velocities as observed early on. The deflagration velocity is close to the laminar deflagration $(v =0.03 c_s)$, and the transition from the deflagration to the detonation occurs at $ρ_{tr} = 2.~10^7 g/cm^{3}$. The initial central density of the white dwarf (WD) is $2.7~10^9 g/cm^{3}$. The distance to SN1994D is determined to $16.2 \pm 2 Mpc$. The explosion took