Abundance stratification in Type Ia supernovae - V. SN 1986G bridging the gap between normal and subluminous SNe Ia

Abstract

A detailed spectroscopic analysis of SN 1986G has been performed. SN 1986G `bridges the gap' between normal and subluminous Type Ia supernovae (SNe Ia). The abundance tomography technique is used to determine the abundance distribution of the elements in the ejecta. SN 1986G was found to be a low-energy Chandrasekhar mass explosion. Its kinetic energy was 70 per cent of the standard W7 model (0.9 × 10<SUP>51</SUP> erg). Oxygen dominates the ejecta from the outermost layers down to ∼9000 km s<SUP>-1</SUP>, intermediate mass elements (IMEs) dominate from ∼9000 to ∼3500 km s<SUP>-1</SUP> with Ni and Fe dominating the inner layers < ∼3500 km s<SUP>-1</SUP>. The final masses of the main elements in the ejecta were found to be, O = 0.33 M<SUB>☉</SUB>, IME = 0.69 M<SUB>☉</SUB>, stable NSE = 0.21 M<SUB>☉</SUB>, <SUP>56</SUP>Ni = 0.14 M<SUB>☉</SUB>. An upper limit of the carbon mass is set at C = 0.02 M<SUB>☉</SUB>. The spectra of SN 1986G consist of almost exclusively singly ionized species. SN 1986G can be thought of as a low-luminosity extension of the main population of SN Ia, with a large deflagration phase that produced more IMEs than a standard SN Ia.