(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?
(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?
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DOI：
10.3847/1538-4357/aca072
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发表时间：
2022-12
期刊：
影响因子：
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通讯作者：
I. De Moortel;T. Howson
中科院分区：
文献类型：
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作者：
I. De Moortel;T. Howson
为什么太阳的大气层比其表面热几个数量级是太阳物理学中长期存在的问题。多年来，许多研究都在研究磁流体动力（MHD）波在维持这些高温方面的潜在作用。在本研究中，我们使用 3D MHD 模拟来研究日冕环中的（驱动）横波。当边界驱动的横波沿着通量管传播时，径向密度分布会导致通量管边界处的共振吸收（或模式耦合）和相混合，并且大速度剪切会受到开尔文-亥姆霍兹不稳定性（KHI）的影响。这些效应的结合导致能量耗散和波浪加热的增强。考虑到谐振和非谐振边界驱动以及通量管的不同密度，我们表明，只有与较低密度环路（环路芯密度为∼5 × 10−13 kg m−3）中的谐振驱动器相关的波加热才能平衡环路壳中的辐射损耗。更改模型参数以考虑更密集的环路或具有非谐振频率的驱动器，或两者兼而有之，会导致日冕环路冷却，因为能量损失大于能量注入和耗散率。
Why the atmosphere of the Sun is orders of magnitudes hotter than its surface is a long standing question in solar physics. Over the years, many studies have looked at the potential role of magnetohydrodynamic (MHD) waves in sustaining these high temperatures. In this study, we use 3D MHD simulations to investigate (driven) transverse waves in a coronal loop. As the boundary-driven transverse waves propagate along the flux tube, the radial density profile leads to resonant absorption (or mode coupling) and phase mixing in the boundaries of the flux tube and the large velocity shears are subject to the Kelvin–Helmholtz instability (KHI). The combination of these effects leads to enhanced energy dissipation and wave heating. Considering both resonant and nonresonant boundary driving as well as different densities for the flux tube, we show that only wave heating associated with a resonant driver in a lower-density loop (with a loop core density ∼5 × 10−13 kg m−3) is able to balance radiative losses in the loop shell. Changing the model parameters to consider a denser loop or a driver with a nonresonant frequency, or both, leads to cooling of the coronal loop as the energy losses are greater than the energy injection and dissipation rates.