Authors: Jiong Qiu (Montana State University)

A solar flare releases 10$^{30-31}$ erg free magnetic energy in minutes. This energy finally manifests itself in prominently enhanced radiation across the EM spectrum, sometimes persisting for several hours. Abundant X-ray and extreme ultraviolet photons are produced in the flare corona, which, apart from being hot, must have its density increased by orders of magnitudes. The mass of the flare corona is obtained through “chromosphere evaporation”, driven by energy deposition in the chromosphere. Imaging observations in the past decade have demonstrated that a solar flare is a collection of multiple energy release events, forming  hundreds of flare loops. Spectroscopic observations and one-dimensional radiative hydrodynamic simulations of the flare chromosphere have been used to find out how much mass may be transported to the corona along a loop. It is however not entirely clearly in what form energy is deposited in the chromosphere, and on what temporal and spatial scales, to maintain the bright corona from the impulsive through the gradual phase of a flare. In this talk, we discuss state-of-the-art flare observations and several models that look for answers to these questions, by examining both the corona and the chromosphere.