Coronal heating problem

The Sun’s outer atmosphere is much hotter than its visible surface. What carries energy there and turns it into heat?[1] [2] [4]

Above the Sun’s visible surface lies a much hotter atmosphere: the corona. What supplies its energy, and where and how is that energy converted to heat? In a magnetic loop linking two areas near the surface, motions can twist or tangle the field. Changing the field’s connections can then release energy into the electrically charged gas, or plasma. Waves provide another transport and heating route. Small heating bursts describe the timing and scale of release; they need not be a separate mechanism from waves or reconnection. For a loop heated by repeated bursts, short intervals let it remain hot, while longer intervals allow cooling between events. That comparison helps interpret radiation patterns, but it does not settle the energy budget of every coronal environment.[1] [2] [3] [4] [5]

Several processes can heat particular regions. Their combined contribution across the corona is still unsettled.[1] [2]

Detecting a heating process in one region does not establish its contribution everywhere. Substantial progress leaves the multiscale coupling and relative heating contributions incompletely explained.[1] [2] [3]

The hot corona emits X-rays and ultraviolet light and is part of the Sun’s changing magnetic environment. Explaining its energy supply would strengthen the physics used to understand space weather, which can disrupt satellites and communications.[1] [4] [5]

An energy-transfer account would connect the corona’s temperature and radiation to the magnetic activity that influences space weather.[1] [5]