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

TL;DR

This paper presents a detailed spectroscopic analysis of SN 1986G, a Type Ia supernova that bridges the gap between normal and subluminous SNe Ia, revealing its unique abundance distribution and explosion characteristics.

Contribution

It introduces the first detailed abundance tomography of SN 1986G, showing it as a low-energy Chandrasekhar mass explosion with a distinct element stratification.

Findings

SN 1986G is a low-energy Chandrasekhar mass explosion.

Oxygen dominates the outer ejecta, with IMEs and Ni/Fe in inner layers.

SN 1986G is a low luminosity extension of normal SNe Ia with a large deflagration phase.

Abstract

A detailed spectroscopic analysis of SN 1986G has been performed. SN 1986G `bridges the gap' between normal and sub luminous type Ia supernova (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% of the standard W7 model (0.9x10$^{51}$erg). Oxygen dominates the ejecta from the outermost layers down to $\sim$9000kms$^{-1}$ , intermediate mass elements (IME) dominate from $\sim$ 9000kms$^{-1}$ to $\sim$ 3500kms$^{-1}$ with Ni and Fe dominating the inner layers $<\sim$ 3500kms$^{-1}$. The final masses of the main elements in the ejecta were found to be, O=0.33M, IME=0.69M, stable NSE=0.21M, $^{56}$Ni=0.14M. An upper limit of the carbon mass is set at C=0.02M. The spectra of SN1986G consist of almost exclusively singly ionised species. SN1986G 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.