发表机构
Hamburger Sternwarte, Universität Hamburg; Institut für Sonnenphysik (KIS)（汉堡天文台，汉堡大学; 太阳物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过三维磁流体模拟，揭示了旋转对红巨星对流、角动量输运及发电机效率的系统性影响。
AI 中文摘要
理解红巨星的内部动力学对于研究恒星演化过程中的角动量输运和磁场产生至关重要。我们利用Pencil Code，采用“星在盒中”的设置，对红巨星分支底部的$1M_{\odot}$红巨星进行了三维磁流体动力学模拟，并持续努力改进数值模型。通过改变旋转速率，我们探索了不同的罗斯比数，并识别出对流动力学和大尺度流动的系统性变化。随着旋转增强，对流运动变得更加各向异性，显示出旋转约束的清晰特征以及主导对流尺度的转变。这些变化伴随着较差自转剖面的变化，反映了对流包层内角动量的重新分布。旋转的影响也体现在磁场的增长率和饱和水平上，表明发电机效率对底层流动结构有很强的依赖性。综合来看，这些结果凸显了对流、旋转和大尺度流动在塑造红巨星磁活动中的相互作用。
英文摘要
Understanding the internal dynamics of red giants is essential for studying angular momentum transport and magnetic field generation during stellar evolution. We present three-dimensional magnetohydrodynamic simulations of a $1M_{\odot}$ red giant at the bottom of the red giant branch using a star-in-a-box setup with the Pencil Code, together with ongoing efforts to refine the numerical model. By varying the rotation rate, we explore different Rossby numbers and identify systematic changes in the convective dynamics and large-scale flows. As the rotation increases, convective motions become more anisotropic, showing clear signatures of rotational constraint and a shift in the dominant convective scales. These changes are accompanied by variations in the differential rotation profile, reflecting the redistribution of angular momentum within the convective envelope. The impact of rotation is also evident in the growth rate and saturation level of the magnetic field, indicating a strong dependence of dynamo efficiency on the underlying flow structure. Together, these results highlight the interplay between convection, rotation, and large-scale flows in shaping magnetic activity in red giant stars.
Comments6 pages, 6 figures. The 23rd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS23), Tokyo, Japan, 15-19 June 2026
