Hydrogen-Poor Circumstellar Shells from Pulsational Pair-Instability Supernovae with Rapidly Rotating Progenitors

TL;DR

This paper investigates how rapidly rotating massive stars undergo pulsational pair-instability, eject hydrogen-poor shells, and influence supernova characteristics, with implications for early stars and superluminous supernovae.

Contribution

It provides new insights into the composition and dynamics of shells ejected by pulsational pair-instability in rapidly rotating progenitors.

Findings

Ejected shells are hydrogen-poor and rich in helium and oxygen.

Rapid rotation (>30% critical) influences the shell composition and dynamics.

Implications for early star evolution and superluminous supernovae phenomena.

Abstract

In certain mass ranges, massive stars can undergo a violent pulsation triggered by the electron/positron pair instability that ejects matter, but does not totally disrupt the star. After one or more of these pulsations, such stars are expected to undergo core-collapse to trigger a supernova explosion. The mass range susceptible to this pulsational phenomena may be as low as 50-70 Msun if the progenitor is of very low metallicity and rotating sufficiently rapidly to undergo nearly homogeneous evolution. The mass, dynamics, and composition of the matter ejected in the pulsation are important aspects to determine the subsequent observational characteristics of the explosion. We examine the dynamics of a sample of stellar models and rotation rates and discuss the implications for the first stars, for LBV-like phenomena, and for superluminous supernovae. We find that the shells ejected by pulsational pair-instability events with rapidly rotating progenitors (>30% the critical value) are hydrogen-poor and helium and oxygen-rich.