Measuring plasma velocities in Coronal loops using Hinode/EIS spectroscopic data to constrain physical models

Abstract

The solar corona (over 10⁶ K) is the hot atmosphere above the surface of the sun (photosphere ~5,000 K).  The corona is composed of plasma that traces the Sun’s complex magnetic field and plays a central role in the transport and release of energy through the solar atmosphere.  Preliminary results of a full-fledged model of the coronal heating problem suggests the interaction between Alfvén waves and nanoflares, although there is a gap in how these interact to create such high temperatures in the corona. By using a Python-based analysis tool developed with the EISPAC framework, we analyzed data from the EIS aboard the Hinode satellite to measure plasma velocities within magnetic loops through Doppler shifts in extreme-ultraviolet emission lines. Our preliminary results of the plasma velocities are not consistent with current computer models. One set of measurements showed mostly upward flow (20 km/s), and another wavelength yielded a line that was less stable and with a downflow (5 km/s). It’s possible that this mismatch is caused by the difficulty of tracing loops consistently in EIS images. This mismatch may support plasma flow varying with temperature inside the loop. Accurately measuring physical properties within these structures, including plasma velocities, provides critical observational constraints for improving models of solar activity and space weather forecasting.