CAN TRACE EXTREME-ULTRAVIOLET OBSERVATIONS OF COOLING CORONAL LOOPS BE USED TO DETERMINE THE HEATING PARAMETERS?

摘要

Recent analysis of relatively cool (～1 MK) active region loops observed with TRACE has suggested that these loops have been heated impulsively and are cooling through the TRACE bandpasses. In this Letter we explore the evolution of cooling loops to determine if the TRACE EUV observations can be used to determine the magnitude, duration, and location of the energy release. We find that the evolution of the apex density and temperature in an impulsively heated cooling loop depends only on the total energy deposited (not the magnitude, duration, or location of the energy deposition) after the loop cools past an "equilibrium point," where the conductive and radiative cooling times are comparable. Hence, observations must be made early in the evolution of a loop to determine the heating parameters. Typical TRACE observations of cooling loops do not provide adequate information to discriminate between different heating scenarios.