  What physical mechanisms heat the outer solar or stellar atmosphere to
million-Kelvin temperatures is a fundamental but long-standing open question.
In particular, the solar corona in active region cores contains an even hotter
component reaching ten million Kelvin, manifesting as persistent coronal loops
in extreme ultraviolet and soft X-ray images, which imposes a more stringent
energy budget. Here, we present a self-consistent coronal heating model using a
state-of-the-art three-dimensional radiative magnetohydrodynamics simulation.
We find that the continuous magnetic flux emergence in active regions keeps
driving magnetic reconnections that release energy impulsively but, on time
average, persistently. As a result, numerous sub-structures are heated to ten
million Kelvin and then evolve independently, which collectively form
long-lived and stable coronal loops as in observations. This provides a heating
model explaining the origin of the super-hot coronal plasma and the persistence
of hot coronal loops in emerging active regions.
