AI 中文总结
本文研究类太阳恒星差旋层中alpha系数的垂直与纬度梯度激发的新型大尺度alpha_theta波，其色散特性与普通发电机波不同，可顺行或逆行，时间尺度从数百天到数十年，还会与Rossby波耦合实现能量转换。
AI 中文摘要
穿透类太阳恒星差旋层的对流所产生的平均湍流电动势的垂直梯度（由发电机系数alpha表示）会导致非传播性的alpha模式，进而引发磁场水平分量的周期性变化。本文旨在研究发电机系数的纬度变化对类太阳恒星差旋层过冲层中大尺度波线性动力学的影响。我们采用简单矩形几何下含发电机系数的线性磁流体动力学（MHD）方程进行研究。结果表明，alpha系数的垂直梯度在感应方程中的形式与动量方程中的科里奥利力相同，因此alpha参数的纬度变化会激发类似旋转球上Rossby波的新型大尺度波。这些波的色散特性仅取决于alpha参数的垂直和纬度梯度，因此其模式与普通发电机波有本质区别。alpha_theta波的传播方向（顺行或逆行）取决于梯度的符号，其时间尺度在太阳差旋层的不同参数下可从数百天到数十年不等。在存在大尺度磁场时，这些波会与旋转球上的Rossby波耦合，可能导致对流能量与旋转能量相互转换。
英文摘要
Vertical gradient of mean turbulent electromotive force (expressed by the dynamo coefficient, alpha, caused by the penetrating convection into the tachoclines of Sun-like stars leads to the non-propagating alpha-mode patterns, which result in the periodic variations of magnetic field horizontal components. The aim of the paper is to study the influence of the latitudinal variation of the dynamo coefficient on the linear dynamics of large-scale waves in the overshoot layers of the tachoclines in Sun-like stars. We use the linear magnetohydrodynamic (MHD) equations with the dynamo coefficient in a simple rectangular geometry. It is shown that the vertical gradient of the alpha coefficient has the same appearance in the induction equation as the Coriolis force in the momentum equation. Therefore, the latitudinal variation of alpha parameter excites new large-scale waves similar to the Rossby waves on a rotating sphere. The dispersion properties of the waves depend only on vertical and latitudinal gradients of the alpha parameter, therefore the modes are basically different from the ordinary dynamo waves. The alpha_theta waves may have either prograde or retrograde propagation depending on the signs of the gradients. The time scales of the waves may vary from hundreds of days to tens of years in various parameters of the solar tachocline. These waves are coupled with the Rossby waves on a rotating sphere in the existence of the large scale magnetic field, which may lead to the mutual transformation of convective and rotation energies.
Comments8 pages, 5 figures, accepted iin MNRAS
