The influence of late-stage nuclear burning on red supergiant supernova light curves

TL;DR

This study models how late-stage nuclear burning in red supergiants influences supernova light curves and pre-explosion outbursts, aligning simulations with observed diversity in Type II supernovae.

Contribution

It demonstrates that wave-induced mass ejection during late nuclear burning can significantly alter supernova light curves and pre-SN outbursts, providing a new explanation for observed phenomena.

Findings

Small energy depositions (~10^{46}-10^{47} erg) affect SN light curves.

Nuclear burning episodes can cause pre-SN outbursts 50-350 days before explosion.

Models explain early spectral features like flash-ionization lines.

Abstract

Many Type II supernovae (SNe) show hot early (~30 days) emission, and a diversity in their light curves extending from the Type IIP to the Type IIL, which can be explained by interaction with dense and confined circumstellar material (CSM). We perform hydrodynamical simulations of red supergiants to model the ejection of CSM caused by wave heating during late-stage nuclear burning. Even a small amount of deposited energy ($10^{46}-10^{47}$ erg), which is roughly that expected due to waves excited by convection in the core, is sufficient to change the shapes of SN light curves and bring them into better agreement with observations. As a test case, we consider the specific example of SN 2017eaw, which shows that a nuclear burning episode is able to explain the light curve if it occurs ~150-450 days prior to core-collapse. Due to the long timescale it takes for the low energy shock to traverse the star, this would manifest as a pre-SN outburst ~50-350 days prior to the full-fledged SN. Applying work like this to other SNe will provide a direct connection between the SN and pre-SN outburst properties, which can be tested by future wide field surveys. In addition, we show that our models can qualitatively explain the short lived `flash-ionization' lines seen in the early spectra of many Type II SNe.