Eruption of the Envelope of Massive Stars by Energy Injection with Finite Duration

Abstract

A significant fraction of supernovae show signatures of dense circumstellar material (CSM). While multiple scenarios for creating a dense CSM exist, mass eruption due to injection of energy at the base of the outer envelope is a likely possibility. We carry out radiation hydrodynamical simulations of eruptive mass loss from a typical red supergiant progenitor with an initial mass of 15 M ⊙, for the first time focusing on the timescale of the injection as well as energy. We find that not only sufficient injection energy but also sufficient rate of energy injection per unit time, L min ∼ 8 × 1040 erg s−1 in this particular model, is required for eruption of unbound CSM. This result suggests that the energy injection rate needs to be greater than the binding energy of the envelope divided by the dynamical timescale for the eruption. The density profile of the resulting CSM, whose shape was analytically and numerically predicted in the limit of instantaneous energy injection, similarly holds for a finite injection timescale. We discuss our findings in the framework of proposed mass outburst scenarios, specifically wave-driven outbursts and common-envelope ejection.

3D Hydrodynamics of Pre-supernova Outbursts in Convective Red Supergiant Envelopes

“…Our range of mass loss rate 10 −2 -10 −1 M e yr −1 also overlaps with the estimated pre-explosion mass loss rates from an unbiased sample of Type IIn SNe, supporting the notion that typical Type IIn SNe may arise from energetic mass eruptions preceding the explosions (Kiewe et al 2012). The formation of shocks upon energy deposition and their traversal through the entire stellar envelope are in good general agreement with previous 1D hydrodynamical models (Dessart et al 2010;Coughlin et al 2018;Fernández et al 2018;Ko et al 2022;Linial et al 2021). Since we opted to focus on nonterminal energy deposition with E dep  E bind , our models are qualitatively comparable to the partial ejection and inflated models in Dessart et al (2010).…”

“…We initialized our stellar envelope based on a MESA RSG progenitor model. The MESA model profiles were generated from a ZAMS mass of 15 M e , representative of the models used in many previous studies (Ouchi & Maeda 2019;Leung & Fuller 2020;Morozova et al 2020;Ko et al 2022). Models in our simulation suite differ in the initial envelope structure (convective or static), amounts and rates of energy deposition, as well as geometry (1D and 3D).…”

“…With E dep = 0.5 E bind , we found that a higher energy deposition rate led to more ejected mass. Ko et al (2022) have emphasized the necessary consideration of energy injection rate in the study of eruptive mass loss from massive stars. With the same amount of energy deposited at a lower rate, gravity effectively has a longer time in which to act and decelerate the shocked gas, reducing the amount of gas above the escape velocity and the final mass loss.…”

“…In order to understand pre-SN outbursts and the associated mass eruptions, many theoretical studies have explored how RSG envelopes react to energy deposition hydrodynamically (Dessart et al 2010;Quataert et al 2016;Kuriyama & Shigeyama 2020;Morozova et al 2020;Ko et al 2022;Linial et al 2021). Based on various 1D stellar models, their main conclusions are: (1) injection of energy comparable to the RSG envelope's binding energy can lead to mass ejection and CSM formation;…”

Supernova Precursor Emission and the Origin of Pre-explosion Stellar Mass Loss

“…unbinding a portion of its mass (Dessart et al 2010;Kuriyama & Shigeyama 2020;Ko et al 2022;Linial et al 2021). Although we remain indifferent to the origin of the sudden energy injection, one possible physical realization would be a dynamical instability associated with unstable nuclear shell burning.…”