标题： 太阳内部磁场管的成功与失败浮现 显示英文标题

标题： Successful and Failed Flux Tube Emergence in the Solar Interior

摘要： 我们报道了关于圆柱形弱扭转磁通管从光球以下18兆米深处浮现的三维（3D）磁流体力学（MHD）模拟。通过改变初始磁场强度（$B_0$）、半径（$R$）、扭曲度（$\alpha)$）和磁通管浮现部分的长度（$\lambda$），我们进行了参数研究，以探讨这些参数如何影响磁场从对流区传递到光球的过程。我们表明，光球处浮现的效率（即与$B_0$相比光球磁场的强度）不仅取决于$B_0$，还取决于浮现磁场的形态和扭曲度。我们还表明，诸如$B_0$和磁通量等参数不能单独决定磁通管是否能浮现到太阳表面。 例如，在光球层，强（弱）$B_0$（$B_0$）磁场可能无法（能够）浮现出来，这取决于它们的几何特性。我们还表明，对于具有相同$B_0$但不同几何特性的磁通管，光球磁场强度可能会有很大差异。此外，在某些情况下，我们发现了标度律，即磁场强度与局部密度之间的关系为$B\propto \rho^\kappa$，其中$\kappa \approx 1$位于对流区深处，$\kappa <1$则接近光球层。 两种数值之间的转换大约发生在局部压力尺度（$H_p$）变得与通量管的直径（$H_p\approx2R$）相当的时候。 我们推导出一些形式来解释这些比例律出现的方式和时间，并将它们与数值模拟进行比较。 显示英文摘要

摘要： We report on our three-dimensional (3D) magnetohydrodynamic (MHD) simulations of cylindrical weakly twisted flux tubes emerging from 18 Mm below the photosphere. We perform a parametric study, by varying the initial magnetic field strength ($B_0$), radius ($R$), twist ($\alpha)$ and length of the emerging part of the flux tube ($\lambda$) to investigate how these parameters affect the transfer of the magnetic field from the convection zone to the photosphere. We show that the efficiency of emergence at the photosphere (i.e. how strong the photospheric field will be in comparison to $B_0$) depends not only on the $B_0$ but also the morphology of the emerging field and the twist. We show that parameters such as $B_0$ and magnetic flux cannot alone determine whether a flux tube will emerge to the solar surface. For instance, high-$B_0$ (weak-$B_0$) fields may fail (succeed) to emerge at the photosphere, depending on their geometrical properties. We also show that the photospheric magnetic field strength can vary greatly for flux tubes with the same $B_0$ but different geometric properties. Moreover, in some cases we have found scaling laws, whereby the magnetic field strength scales with the local density as $B\propto \rho^\kappa$, where $\kappa \approx 1$ deeper in the convection zone and $\kappa <1$, close to the photosphere. The transition between the two values occurs approximately when the local pressure scale ($H_p$) becomes comparable to the diameter of the flux tube ($H_p\approx2R$). We derive forms to explain how and when these scaling laws appear and compare them with the numerical simulations.