One-, Two-, and Three-dimensional Simulations of Oxygen-shell Burning Just before the Core Collapse of Massive Stars

Abstract

We perform two-(2D) and three-dimensional (3D) hydrodynamics simulations of convective oxygen shell-burning that takes place deep inside a massive progenitor star of a core-collapse supernova. Using one dimensional (1D) stellar evolution code, we first calculate the evolution of massive stars with an initial mass of 9-40 M . Four different overshoot parameters are applied, and CO core mass trend similar to previous works is obtained in the 1D models. Selecting eleven 1D models that have a silicon and oxygen coexisting layer, we perform 2D hydrodynamics simulations of the evolution for ∼100 s until the onset of core-collapse. We find that convection with large-scale eddies and the turbulent Mach number ∼0.1 is obtained in the models having a Si/O layer with a scale of 10 8 cm, whereas most models that have an extended O/Si layer up to a few ×10 9 cm exhibit lower turbulent velocity.Our results indicate that the supernova progenitors that possess a thick Si/O layer could provide a preferable condition for perturbation-aided explosions. We perform 3D simulation of a 25 M model, which exhibits large-scale convection in the 2D models. The 3D model develops large-scale ( = 2) convection similar to the 2D model, however, the turbulent velocity is lower. By estimating the neutrino emission properties of the 3D model, we point out that a time modulation of the event rates, if observed in KamLAND and Hyper-Kamiokande, would provide an important information about structural changes in the presupernova convective layer.

A Subsolar Metallicity Progenitor for Cassiopeia A, the Remnant of a Type IIb Supernova

“…We calculate the evolution of 15 M stars with metallicities of Z = 0.014(Z ), 0.5Z , 0.2Z , and 0 from hydrogen burning until the central temperature reaches 10 9.9 K. For metallicities of 0.5Z , we also calculate the evolution for 13, 17, and 20 M stars. These calculations are performed using a 1D stellar evolution code, HOngo Stellar Hydrodynamics Investigatar (HOSHI) code (Takahashi et al 2016(Takahashi et al , 2018(Takahashi et al , 2019Yoshida et al 2019). Detailed parameter sets of the stellar models are the same as Set L in Yoshida et al (2019).…”

Radiative-transfer modeling of nebular-phase type II supernovae

“…Collins et al (2018) report a higher occurrence of merging for the O, Ne, and C burning shells in higher mass progenitors between 16 and 26 M , yielding a large Si mass fraction in a large part of the O-rich shell -this is the same as what we observe in our MESA simulations. Similarly, Yoshida et al (2019) obtain distinct composition profiles within the Si-and O-rich shells depending on the adopted convective overshoot strength and progenitor mass.…”

Fitting formulae for evolution tracks of massive stars under extreme metal-poor environments for population synthesis calculations and star cluster simulations

“…Our simulation method is similar to 1 dimensional (1D) simulation method in Yoshida et al (2019). We follow the time evolutions of stars with M = 8, 10,13,16,20,25,32,40,50,65,80,100,125, and 160 M for log(Z/Z ) = -2, -4, -5, -6 and −8 from the zero age main-sequence (ZAMS) to the carbon ignitions at the stellar centers.…”