Coronal Energetics and Loop Dynamics

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An accurate determination of the plasma temperature distribution is an essential first step to understanding the dynamics, density, and filling factor of coronal loops, the closed magnetic field structures filled with hot plasma that dominates the high-energy emissions from the Sun. These quantities are important inputs in determining, e.g., the energy balance and heating requirements of a region, coronal loop stability, and calculations of radiative losses and conductive cooling in a given feature. This proposed effort will examine the temperature profile, density structure, and temporal evolution of coronal loops. With this information, and by using estimates of the coronal magnetic field, elemental abundances, bulk flows, waves, and turbulent motions from previous measurements, the dominant energy loss mechanisms can be determined for different (and possibly different types of) coronal loops.This project combines high-resolution EUV spectral line data from the SOlar and Heliospheric Observatory (SOHO) Coronal Diagnostics Spectrometer with EUV and X-ray imaging data from other instruments. These observational results will be compared with the temperature profiles predicted by various coronal-heating mechanisms in order to determine which of these mechanisms, if any, is responsible for the loop heating. The detailed quantitative results will be made available to theoreticians studying coronal heating. In addition, this investigation will provide improved temperature cross-calibrations of the instruments and a quantification of the uncertainties inherent in the use of the individual data sets. The resulting algorithms will be made available to the scientific community by integrating them into existing software libraries.Graduate and undergraduate students will play a vital role in the proposed analysis. The associated outreach project, Breaking the Secret Code of Starlight, introduces 5th graders from the Memphis inner-city school system to the basics of spectroscopy by answering the question, What are stars made of? Too many local students think the answer has more to do with magic than with physics. Starlight teaches students how scientists use spectroscopy to find the answer. Groups of 5th graders come to the University on field trips to participate in the Starlight program, or teams of undergraduates bring Starlight directly to the classrooms. The program started small, with about 10 classes of 25 students each, but the number of students and teachers who have participated in Starlight has now reached 5000.