标题： 非对称性在日冕雨形成中的作用——热非平衡循环方面 显示英文标题

标题： The role of asymmetries in coronal rain formation during thermal non-equilibrium cycles

摘要： 背景：热非平衡（TNE）会产生若干可观测现象，可用于限制太阳日冕加热的空间和时间分布。 其表现包括日珥形成、日冕雨以及日冕环中的长时间强度脉动。 Auchère等人最近观测到丰富的周期性日冕雨与强度脉动相关联，这使我们可以将这两种现象统一为TNE冷凝和蒸发循环的结果。 另一方面，Froment等人观察到的许多强度脉动事件几乎没有或完全没有日冕雨的形成。 目标：我们的目标是理解为什么某些TNE循环会产生如此丰富的日冕雨，而其他循环却几乎没有或没有日冕雨。 方法：我们使用STEREO/SECCHI/EUVI的图像和SDO/HMI的磁图重构了Auchère等人报告的事件的几何结构。 然后，我们针对不同的加热参数和环几何形状的变化（总计9000次模拟），对该事件进行1D流体力学模拟。 我们将所得结果与Froment等人模拟的未产生日冕雨的TNE循环进行比较。 结果：我们的模拟显示，日珥和TNE循环（有无日冕雨）都可以在同一磁结构中形成。 我们表明，在TNE循环中日冕雨的形成取决于环的不对称性和加热情况。 不对称环总体上不太可能产生日冕雨，无论加热如何。 在对称环中，当加热也对称时，日冕雨会形成。 在不对称环中，只有当加热补偿了不对称性时，才会形成雨。 显示英文摘要

摘要： Context: Thermal non-equilibrium (TNE) produces several observables that can be used to constrain the spatial and temporal distribution of solar coronal heating. Its manifestations include prominence formation, coronal rain, and long-period intensity pulsations in coronal loops. The recent observation of abundant periodic coronal rain associated with intensity pulsations by Auch\`ere et al. allows to unify these two phenomena as the result of TNE condensation and evaporation cycles. On the other hand, many intensity pulsation events observed by Froment et al. show little to no coronal rain formation. Aims: Our goal is to understand why some TNE cycles produce such abundant coronal rain, while others produce little to no rain. Methods: We reconstruct the geometry of the event reported by Auch\`ere et al., using images from STEREO/SECCHI/EUVI and magnetograms from SDO/HMI. We then perform 1D hydrodynamic simulations of this event, for different heating parameters and variations of the loop geometry (9000 simulations in total). We compare the resulting behaviour to simulations of TNE cycles by Froment et al. that do not produce coronal rain. Results: Our simulations show that both prominences and TNE cycles (with and without coronal rain) can form within the same magnetic structure. We show that the formation of coronal rain during TNE cycles depends on the asymmetry of the loop and of the heating. Asymmetric loops are overall less likely to produce coronal rain, regardless of the heating. In symmetric loops, coronal rain forms when the heating is also symmetric. In asymmetric loops, rain forms only when the heating compensates the asymmetry.