| Presentation Title: | Characterizing Hot Plasma in Solar Active Regions via HXR Differential Emission Measure Analysis |
| Author(s): | Jessie Duncan, Reed B. Masek, Albert Y. Shih, Lindsay Glesener, Will Barnes, Katharine K. Reeves, Iain G. Hannah |
Abstract:
Solar active regions (ARs) contain plasma across a broad range of temperatures, with the thermal distribution often observed to peak in the few millions of kelvin. Hard x-ray observations are uniquely sensitive to extremely hot (>10 MK) material, and are therefore essential for diagnosing the very hottest components of ARs. At quiet times, constraining this ultra-hot material is a crucial diagnostic of the frequency of heat input leading to the elevated temperature of the corona. Differential emission measure (DEM) analysis uses observations by instruments sensitive to thermal plasma to estimate the amount of material present as a function of temperature. DEMs with HXR constraints are so far fairly limited in the literature, but represent an exciting opportunity to investigate hot AR plasma. The Nuclear Spectroscopic Telescope ARray (NuSTAR) is a sensitive HXR observatory which makes periodic observations of the Sun. Combining NuSTAR’s HXR coverage with other instruments (AIA, XRT), we perform time-resolved DEMs to characterize the thermal evolution of ARs. We discuss initial results from these NuSTAR DEMs, in conjunction with future prospects for gaining further insight about active region heating using HXR observation.