Abundance stratification in Type Ia supernovae - III. The normal SN 2003du

TL;DR

This study models the element distribution in the ejecta of the normal Type Ia supernova SN 2003du, revealing detailed stratification and composition that inform understanding of explosion mechanisms.

Contribution

It provides a detailed abundance stratification model for SN 2003du, a representative normal Type Ia supernova, based on spectral analysis, highlighting the layered structure of elements.

Findings

Inner layers dominated by stable Fe-group elements (~0.2 Msun)

Total 56Ni mass of 0.65 Msun

Outer layers mainly oxygen with some silicon

Abstract

The element abundance distributions in the ejecta of Type Ia supernova (SN) is studied by modelling a time series of optical spectra of SN 2003du until ~1 year after the explosion. Since SN 2003du is a very normal Type Ia SN both photometrically and spectroscopically, the abundance distribution derived for it can be considered as representative of normal Type Ia SNe. We find that the innermost layers are dominated by stable Fe-group elements, with a total mass of ~ 0.2 Msun, which are synthesized through electron capture. Above the core of stable elements there are thick 56Ni-rich layers. The total mass of 56Ni is 0.65 Msun. The Si- and S-rich layers are located above the 56Ni-rich layers. The dominant element in the outermost layers (M_r > 1.1 Msun, v > 13000 km/s) is O, with a small amount of Si. Little unburned C remains, with an upper limit of 0.016 Msun. The element distributions in the ejecta are moderately mixed, but not fully mixed as seen in three-dimensional deflagration models.