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

从理论和模型的角度来看，太阳色球层的物理学是复杂的。在色球层中，从光球到日冕的等离子体温度从5,000 K增加到100万K，距离仅为10,000 km。这是如何发生的是当今太阳物理学中最大的谜团。本项目通过对几个NSF和NASA数据集的观察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。该项目由日地研究计划和促进竞争研究的既定计划（EPSCoR）联合资助。本文研究了焦耳加热作为太阳活动区的大气加热机制，特别是在低色球层，其中考林电阻率占主导地位。该团队将把重点放在磁场强度和磁场方向的强梯度普遍存在的目标结构上，这些结构会产生电流，如太阳黑子本影内的光桥（LBs），磁通量出现在无磁场或有磁场的环境中，极性反转线或像埃勒曼炸弹这样的磁重联点。为了进行这项调查，他们将根据天基和地面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表格数据进行最先进的数据约束分析。焦耳加热是电阻率和电流的函数。为了计算考林电阻率，研究小组将色球层建模为由纯氢组成的非lte等离子体，可以用准磁流体力学单流体理论来描述，其中离子和中性离子之间的相互作用伴随着考林电阻率。根据该模型，coling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。该团队将通过应用非无力场（NFFF）外推技术对NASA的太阳动力学观测站矢量磁图获得磁场，通过倒置NASA界面区域成像光谱仪和NSF的邓恩太阳望远镜的光谱数据获得温度、电子密度和/或电子压力，并从理论和半经验大气模型中获得其余的量。他们将进行最先进的数据约束分析，以计算三个不同观测周期内一组目标的焦耳加热。这项研究将对现有的色球加热研究作出重要贡献。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.