Hydrodynamic Simulations of Pre-supernova Outbursts in Red Supergiants: Asphericity and Mass Loss

Abstract

The activity of a massive star approaching core-collapse can strongly affect the appearance of the star and its subsequent supernova. Late-phase convective nuclear burning generates waves that propagate toward the stellar surface, heating the envelope and potentially triggering mass loss. In this work, we improve on previous onedimensional models by performing two-dimensional simulations of the pre-supernova mass ejection phase due to deposition of wave energy. Beginning with stellar evolutionary models of a 15 M e red supergiant star during core O-burning, we treat the rate and duration of energy deposition as model parameters and examine the mass-loss dependence and the pre-explosion morphology accordingly. Unlike one-dimensional models, density inversions due to wave heating are smoothed by Rayleigh-Taylor instabilities, and the primary effect of wave heating is to radially expand the star's hydrogen envelope. For low heating rates with long durations, the expansion is nearly homologous, whereas high but short-lived heating can generate a shock that drives envelope expansion and results in a qualitatively different density profile at the time of core-collapse. Asymmetries are fairly small, and large amounts of mass loss are unlikely unless the wave heating exceeds expectations. We discuss implications for presupernova stellar variability and supernovae light curves.

Fast Blue Optical Transients Due to Circumstellar Interaction and the Mysterious Supernova SN 2018gep

“…Similar to our previous work (Leung & Fuller 2020), when we model the envelope dynamics, we treat the duration of energy deposition as a parameter. This allows us to model the resulting interaction-powered light curve as a function of both the wave-energy deposition and its duration, but we note that the two parameters are linked when modeling the inner core evolution of the star, as investigated in Shiode & Quataert (2014) and Wu & Fuller (2021).…”

“…To explain the origin of the CSM, a number of mechanisms can trigger greatly enhanced mass loss prior to the final stellar explosion, including common-envelope-triggered mass loss (Chevalier 2012;Schrøder et al 2020), pulsation-induced mass loss in pulsational pair-instability SNe (PPISNe; Umeda & Nomoto 2003;Woosley 2017;Marchant et al 2019;Leung et al 2020a;Woosley 2019;Renzo et al 2020a), enhanced stellar wind in super-asymptotic giant branch stars (Jones et al 2013;Moriya et al 2014;Nomoto & Leung 2017;Tolstov et al 2019), and wave-driven mass loss (Quataert & Shiode 2012;Shiode & Quataert 2014;Fuller 2017;Fuller & Ro 2018;Ouchi & Maeda 2019;Leung & Fuller 2020;Kuriyama & Shigeyama 2021).…”

Wave-driven Mass Loss of Stripped Envelope Massive Stars: Progenitor-dependence, Mass Ejection, and Supernovae

“…The energy injection can also change the near-surface structure of the star (Owocki et al 2019;Kuriyama & Shigeyama 2020;Leung & Fuller 2020) and hence its observable optical appearance (Kuriyama & Shigeyama 2021). Additionally, the circumstellar medium can greatly affect the light curve of the subsequent supernova (Suzuki et al 2019).…”

Stellar winds and metal enrichment from fast-rotating Population III stars

“…This is expected since metal-poor material presents only very few absorption lines and thus is not efficient in transforming part of the radiative energy into bulk kinetic energy (Kudritzki 2002). However, this conclusion can be different in rotating stellar models as we shall see below (Meynet et al 2006;Hirschi 2007;Ekström et al 2008a), and/or if mass loss is triggered through processes that are not or weakly dependant on metallicity, such as some kinds of pulsations or instabilities triggered by internal gravity waves (Smith & Owocki 2006;Van Marle et al 2008;Yoon & Cantiello 2010;Fuller 2017;Fuller & Ro 2018;Leung & Fuller 2020;Wu & Fuller 2021).…”