Dependence of Coronal Loop Temperature on Loop Length and Magnetic Field Strength

Abstract

The temperature characteristics of solar coronal loops over a wide range of lengths and magnetic field strengths are investigated by means of numerical simulations. A very high correlation between magnetic field strength (B ₀) and maximum temperature (T _max) is found. Shorter loops rooted at stronger fields are those that reach higher maximum temperatures. High temperatures constitute a small part of the loop volume. For loops of equal length, those with stronger magnetic fields have broader emission measure distributions. The conditions underlying the variety of loops observed in the solar corona are discussed, an explanation of why both cold and hot loops exist is provided, and suggestions are given as to what observations need to be made to confirm the results. Data in the analysis are provided by numerical simulations using HYPERION, an explicit massively parallel Fourier collocation-finite-difference code. In the simulations footpoints are convected with a randomized large-scale flow. This produces a Poynting flux which leads to the buildup of magnetic energy in the loop. The magnetic energy is then transformed into thermal energy by a magnetic reconnection process occurring within current sheets formed locally by an energy cascade toward small scales.