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arXiv 2408.01718astro-ph.SR
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大质量恒星中的巨型爆发及其对恒星结构的影响

Giant Eruptions in Massive Stars and their Effect on the Stellar Structure

Bhawna Mukhija, Amit Kashi

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Accepted for publication in ApJ
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AI总结：

本研究利用 MESA 模拟 70 M⊙ 恒星在主序末期经历持续 20 年的巨型爆发，揭示其膨胀、收缩、光度下降及约 87 年后恢复至近初始状态的结构演化过程。

摘要：

高光度蓝变星（LBVs）中的巨型爆发（GE）是持续数年至数十年的外层物质损失增强阶段，在此期间恒星的物理性质和观测性质会发生重大变化。我们使用 MESA 恒星演化代码来模拟一颗经历巨型爆发的 70 M⊙ 恒星的演化。我们让恒星演化至主序（MS）终止，并在其达到 T ≃ 19 400 K 时，通过从其外层移除物质来模拟一次巨型爆发，物质损失率为 0.15 M⊙ yr⁻¹，持续 20 年。随着物质不断损失，恒星收缩并释放大量引力能。恒星最初经历约 3 天的膨胀，随后是持续数年的收缩。在此期间，恒星试图达到平衡状态，并且由于引力能损失，其光度下降约一个数量级。巨型爆发结束后，我们让恒星在不再发生任何物质损失的情况下继续演化，并追踪其恢复过程：恒星通过调整内部结构重新获得平衡。约 87 年后，它达到了一个非常接近巨型爆发最初开始时的状态。我们认为，在这一时刻可能会发生另一次巨型爆发或一个巨型爆发循环。

英文摘要：

Giant eruptions (GE) in Luminous blue variables (LBVs) are years to decades-long episodes of enhanced mass loss from the outer layers of the star during which the star undergoes major changes in its physical and observed properties. We use the \textsc{mesa} stellar evolution code to model the evolution of a $70~M_{\odot}$ star that undergoes a GE. We let the star evolve to the termination of the main sequence (MS) and when it reaches $T\simeq 19\,400 $ K we emulate a GE by removing mass from its outer layers, at a rate of $0.15~ M_{\odot}~\rm yr^{-1}$ for 20 years. As mass is being lost, the star contracts and releases a substantial amount of gravitational energy. The star undergoes an initial $\simeq 3$ days of expansion followed by years of contraction. During that time the star tries to reach an equilibrium state and as a result of loss in gravitational energy, its luminosity drops about one order of magnitude. As the GE terminates, we let the star continue to evolve without any further mass loss and track its recovery as it regains its equilibrium by adjusting its internal structure. After $\simeq 87$ years it reaches a state very close to the one where the GE was first initiated. We suggest that at this point another GE or a cycle of GEs may occur.

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