论文标题
在阳光恒星中中间MHD波的离子中性阻尼不可避免的后果
Inevitable consequences of ion-neutral damping of intermediate MHD waves in Sun-like stars
论文作者
论文摘要
在太阳大气层的背景下，我们重新审视了中性和电离物种在将中间模式MHD波的有序能量耗散成热量中的作用。我们沿磁场的封闭管求解了流体动力学以及氢和氦电离阶段的保护方程。首先，我们检查了冠状加热突然停止的条件下的冠状血浆的演变。我们发现酷（$ <10^5 $ k）结构持续了几个小时。 MHD幅度的MHD波可以通过离子中性碰撞加热血浆，并具有足够的能量速率，以支持血浆抗重力。然后，我们检查从凉爽气氛开始的计算。该计算表明，通过相同的机制出现温暖（$> 10^4 $）k长（$> $几毫米）的等离子体。我们推测这些溶液与可观察到的太阳特性和相似恒星的相关性，其大气被新兴的磁场渗透并通过对流搅动。也许这个基本过程可能有助于解释太阳过渡区域中``酷循环''的存在以及过渡区域线的广泛组成部分的产生。从如此简单甚至不可避免的机制中生产离子氢的生产可能是寻找产生冠状动脉所需的更复杂机制的重要一步，其温度超过10 $^6 $ K，而与恒星的金属性无关。
In the context of the solar atmosphere, we re-examine the role of of neutral and ionized species in dissipating the ordered energy of intermediate-mode MHD waves into heat. We solve conservation equations for the hydrodynamics and for hydrogen and helium ionization stages, along closed tubes of magnetic field. First, we examine the evolution of coronal plasma under conditions where coronal heating has abruptly ceased. We find that cool ($< 10^5$K) structures are formed lasting for several hours. MHD waves of modest amplitude can heat the plasma through ion-neutral collisions with sufficient energy rates to support the plasma against gravity. Then we examine a calculation starting from a cooler atmosphere. The calculation shows that warm ($> 10^4 $) K long ($>$ several Mm) tubes of plasma arise by the same mechanism. We speculate on the relevance of these solutions to observed properties of the Sun and similar stars whose atmospheres are permeated with emerging magnetic fields and stirred by convection. Perhaps this elementary process might help explain the presence of ``cool loops'' in the solar transition region and the production of broad components of transition region lines. The production of ionized hydrogen from such a simple and perhaps inevitable mechanism may be an important step towards finding the more complex mechanisms needed to generate coronae with temperatures in excess of 10$^6$K, independent of a star's metallicity.
