通过边界层效应形成Be星吸积盘的二维流体动力学模拟
2D hydrodynamical simulations of Be star decretion disc formation through boundary layer effects
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中文总结 AI 辅助
研究Be星吸积盘形成机制，通过二维流体动力学模拟，考虑边界层效应，揭示盘径厚比等因素对吸积盘形成的影响，表明其可通过流体动力学方式形成，对调节恒星自转有重要作用，且一维和二维模型结果一致。
中文摘要 AI 辅助
Be星是大质量主序星，其自转接近瓦解速率。它们有因恒星质量损失形成的吸积盘，但由于其低于瓦解速率的自转速度，吸积盘形成机制尚无定论。我们首次进行了二维流体动力学模拟，研究因边界层效应使靠近恒星处吸积盘转速降低，从而由快速旋转恒星形成Be星吸积盘的过程。在盘径厚比\(h/r = 0.1\)的模拟中，恒星以瓦解速率的\(80\%\)旋转时可形成吸积盘，\(70\%\)时则失败。对于更薄的盘，可能需要更快的恒星自转才能形成动力学上重要的吸积盘。我们还展示了一维和二维模型间的良好一致性。尽管未考虑磁场且角动量传输通过粘性，但结果有力表明Be星盘可通过边界层效应流体动力学方式形成，且可能在调节恒星自转中起关键作用。
英文摘要
Be stars are massive main-sequence stars rotating close to their breakup rate. They possess a decretion disc of material built up due to mass loss from the star, however, there is not a consensus to the mechanism responsible for the formation of the disc because of their sub-breakup spin rates. We present the first 2D hydrodynamical simulations of the formation of a Be star decretion disc from a rapidly rotating star due to boundary layer effects that reduce the rotation rate of the disc close to the star. In our simulations with a disc aspect ratio of $h/r=0.1$, a decretion disc forms around a star rotating with $80 \%$ of the breakup rate, but fails when rotating at $70 \%$ of the breakup rate. For a thinner disc, a faster stellar spin may be needed to form a dynamically important decretion disc. We also demonstrate good agreement between 1D and 2D models. Although this work does not consider the presence of magnetic fields and the angular momentum transport is through viscosity, our results robustly show a Be star disc may be built up hydrodynamically through boundary layer effects, and may play an essential role in regulating the stellar spin.
