SHINE: Joule Heating as a Solar Active Region Atmosphere Heating Mechanism

太阳色球层的物理学从理论和建模的角度来看都是复杂的。从光球到日冕的等离子体温度在色球层中仅10，000 km的距离上从5，000 K增加到100万K。这是如何发生的是当今太阳物理学中最大的谜团。该项目通过对NSF和NASA的几个数据集进行观测研究来调查这一过程。这项工作支持早期职业科学家，包括一名女性博士后研究员和REU学生。该项目由太阳-地球研究计划和刺激竞争研究的既定计划（EPSCoR）共同资助。 本文研究了焦耳加热作为太阳活动区大气加热机制，特别是在Cowling电阻率占主导地位的低色球层。该团队将专注于目标结构，其中磁场强度和磁场方向的强梯度普遍导致电流，如太阳黑子本影内的光桥（LB），磁通量出现在无磁场或磁性环境中，极性反转线或像Ellerman炸弹一样的磁重联点。为了进行这项调查，他们将根据天基和地基太阳观测仪器的观测数据以及理论或半经验太阳大气模型的列表数据进行最先进的数据约束分析。焦耳热的重点是考林电阻率和电流的函数。为了计算Cowling电阻率，该团队将色球层建模为由纯氢组成的非LTE等离子体，可以通过准磁流体动力学单流体理论来描述，其中离子和中性粒子之间的相互作用遵循Cowling电阻率。根据该模型，Cowling电阻率是等离子体体积密度、温度、磁场、电子和离子密度的函数。该团队将通过将非无力场（NFFF）外推技术应用于NASA的太阳动力学天文台矢量磁图来获得磁场，通过反演NASA的界面区域成像光谱仪和NSF的Dunn太阳望远镜的光谱数据来获得温度，电子密度和/或电子压力，以及理论和半经验大气模型的其余数量。他们将进行最先进的数据约束分析，以计算三个不同观测期内一组目标的焦耳加热。这项研究将是对色球加热研究现有努力的重要贡献。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

The physics of the solar chromosphere is complex from both theoretical and modeling perspectives. The plasma temperature from the photosphere to corona increases from 5,000 K to 1 million K over a distance of only 10,000 km in the chromosphere. How this happens is the biggest mystery in solar physics today. This project investigates this process through an observational study of several NSF and NASA data sets. The work supports early career scientists, including a female post-doctoral researcher and REU students. This project is jointly funded by the Solar-Terrestrial Research program and the Established Program to Stimulate Competitive Research (EPSCoR). This work investigates Joule heating as a solar active region atmosphere heating mechanism in particular in the lower chromosphere where Cowling resistivity is dominant. The team will focus on target structures where strong gradients in the magnetic field strength and field orientation are prevalent resulting in currents such as light bridges (LBs) inside the umbra of sunspots, magnetic flux emergence into a field- free or magnetic environment, polarity inversion lines or magnetic reconnection sites like Ellerman bombs. To conduct this investigation, they will make a state-of-the-art data-constrained analysis based on observational data from space-based and ground-based solar observational instruments as well as tabulated data from theoretical or semi-empirical solar atmosphere models. The Joule heating focused on is a function of Cowling resistivity and electric current. To calculate the Cowling resistivity, the team will model the chromosphere as a non-LTE plasma consisting of purely hydrogen which can be described by a quasi-magnetohydrodynamic single-fluid theory in which the interactions between ions and neutrals are followed by the Cowling resistivity. According to this model, Cowling resistivity is a function of plasma bulk density, temperature, magnetic field, electron and ion densities. The team will obtain the magnetic field by applying a non-force-free field (NFFF) extrapolation technique to NASA’s Solar Dynamics Observatory vector magnetograms, the temperature, electron density and/or electron pressure by inverting spectral data from NASA’s Interface Region Imaging Spectrograph and NSF’s Dunn Solar Telescope, and the rest of the quantities from theoretical and semi-empirical atmosphere models. They will make a state-of-the-art data-constrained analysis to calculate the Joule heating for a set of targets in three different observational periods. This investigation will be an important contribution to the existing efforts on chromospheric heating research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.