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

Abstract

Magnetic loops in the outer solar atmosphere (corona) contain plasma heated to approximately 1-6 MK and are fundamental to understanding space weather. Eruptions from these structures can cause significant terrestrial impacts, such as geomagnetic storms and disruptions to communication satellites and power grids. While the long-term goal is to predict these events, current computational models, which utilize conservation of mass, momentum, and energy, first require in-depth observational data to accurately represent the underlying physical processes. The most significant parameters for these models include plasma temperature, density, and, most critically, velocity fields, which are direct indicators of energy transport and instability triggers.

In this study, we provide such observational constraints by measuring plasma velocities within manually identified coronal loops. We use extreme-ultraviolet spectroscopic data from the EUV Imaging Spectrometer (EIS) on the Hinode satellite. By creating and using our very own Python-based analysis tool, developed with the help of the EISPAC module, we interpret Doppler shifts in the spectroscopic data to derive line-of-sight plasma velocities across a temperature range of 500,000 to 6,000,000 Kelvin. These measurements are designed to be inputted into existing theoretical models to test and refine our understanding of the heating and eruption mechanisms in these loops. The results of our velocity measurements, categorized by loop structure, loop position, and plasma formation temperature, will be presented, providing an important dataset for benchmarking magnetohydrodynamic (MHD) simulations.