Constraining the physical properties of Type II-P supernovae using nebular phase spectra

TL;DR

This study analyzes nebular spectra of Type II-P supernovae to understand their physical properties, highlighting the effects of mixing, primordial metals, and linking explosion energy to nickel production.

Contribution

It introduces a detailed spectral analysis method for Type II-P supernovae, emphasizing the importance of primordial metals and explosion mixing in interpreting nebular spectra.

Findings

Strong mixing during explosion explains spectral diversity.

Primordial metals significantly influence emission lines.

Higher explosion energy correlates with increased 56Ni mass.

Abstract

We present a study of the nebular phase spectra of a sample of Type II-Plateau supernovae with identified progenitors or restrictive limits. The evolution of line fluxes, shapes, and velocities are compared within the sample, and interpreted by the use of a spectral synthesis code. The small diversity within the dataset can be explained by strong mixing occurring during the explosion, and by recognising that most lines have significant contributions from primordial metals in the H envelope, which dominates the total ejecta mass in these type of objects. In particular, when using the [O I] 6300, 6364 Angstrom doublet for estimating the core mass of the star, care has to be taken to account for emission from primordial O in the envelope. Finally, a correlation between the H-alpha line width and the mass of 56Ni is presented, suggesting that higher energy explosions are associated with higher 56Ni production.