![]() ![]() The likely ingredients in the coronal solution are magnetic reconnection and dissipation of magnetohydrodynamic waves, but the details remain elusive. ![]() Introduction Recent advances in observations and modelling have shown that magnetohydrodynamic (MHD) waves could signicantly con-tribute to the heating of the solar corona (see review byVan Doorsselaere et al.2020). The chromospheric heating problem is reminiscent of, but more acute than, the coronal heating problem, a perennial challenge to solar physicists. Sun: atmosphere Sun: oscillations magnetohydrodynamics (MHD) waves methods: numerical 1. Acoustic waves apparently contribute some 10% of the deficit, but additional wave energy may yet be discovered at small scales. The losses are a factor of two greater than the gains the difference, about 3000 W/m 2, represents a largely unexplained deficit required to heat the chromosphere. But at the simplest level, far-UV emission (122–200 nm) represents energy lost by the chromosphere, and the depth of the absorption lines at longer wavelengths represents energy inputs from below. Estimates of the radiative gains and losses are sensitive to details of the models. The corona extends outwards for more than a. Conduction from above doesn’t contribute much to chromospheric heating because the thermal conductivity is low. We only see this layer and the other outer layers during an eclipse. ![]() As physicists, we are strongly committed to the principle of conservation of energy, but the chromosphere would be a difficult place to confirm it. ![]()
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