arXiv 2007.117122020-07astro-ph.HEastro-ph.SR

红超巨星前超新星爆发的流体动力学模拟：非球对称性与质量损失

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

Shing-Chi Leung, Jim Fuller

备注：: 21 pages, 44 figures. Submitted to Astrophysical Journal at 25 June 2020, accepted at 3 August 2020. Main text and references updated
发表信息：: Astrophysical Journal 900, 99 (2020)
DOI：: 10.3847/1538-4357/abac5d

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AI总结：

本研究通过二维流体动力学模拟，改进一维模型，研究红超巨星波热沉积引发的前超新星质量抛射，发现低加热率下包层近似同尺度膨胀，高加热率产生激波，非球对称性小，质量损失有限。

摘要：

接近核心坍缩的大质量恒星的活动可以强烈影响恒星的外观及其随后的超新星。晚阶段的对流核燃烧产生的波向恒星表面传播，加热包层并可能触发质量损失。在这项工作中，我们改进了先前的一维模型，通过执行二维模拟来研究由波热沉积引起的前超新星质量抛射阶段。从一颗15 $M_{\odot}$红超巨星在核心氧燃烧阶段的恒星演化模型出发，我们将能量沉积速率和持续时间视为模型参数，并据此检查质量损失依赖性和爆炸前形态。与一维模型不同，由波加热引起的密度反转被瑞利-泰勒不稳定性平滑，波加热的主要效应是使恒星的氢包层径向膨胀。对于低加热速率和长持续时间，膨胀几乎是同尺度的，而高但短暂的加热可以产生激波，驱动包层膨胀，并在核心坍缩时导致定性不同的密度分布。非球对称性相当小，除非波加热超过预期，否则大量质量损失不太可能发生。我们讨论了对前超新星恒星变率和超新星光变曲线的影响。

英文摘要：

The activity of massive stars 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 one-dimensional models by performing two-dimensional simulations of the pre-supernova mass ejection phase due wave heat deposition. Beginning with stellar evolutionary models of a 15 $M_{\odot}$ red supergiant star during core O-burning, we treat the energy deposition rate and duration 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 pre-supernova stellar variability and supernovae light curves.

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