Collaborative Research: Heating the Solar Chromosphere Through Plasma Turbulence

该项目的目标是对太阳大气加热的起源提供详细的、可核查的解释。到达地球的大部分光来自太阳的“表面”，这一区域被称为光球层。然而，太阳表面上方的太阳大气区域，即太阳色球和日冕，产生了大部分危险的紫外线(UV)和X射线辐射。这些区域还会产生太阳风，这是一种带电粒子流，以超过400公里/S的速度穿过地球。快速变化的辐射和太阳风都会对航天器和宇航员造成危险，并对地球产生一些重要的影响。一个长期存在的谜团阻碍了科学家理解色球和日冕并对其进行准确建模。在太阳“表面”上方不远的地方，太阳大气的温度上升了两到三倍。本项目的目的是对这种供暖的来源进行解释。该项目还将提供在波士顿大学招聘和培训等离子体和太阳物理、模拟和建模方面的学生研究人员的机会。波士顿大学派的许多本科生研究顾问，其中大约一半是女性，继续读研究生。这项研究将检验从光球层涌出的太阳等离子体流是否能够将足够的能量转移到太阳大气的湍流等离子体中，这反过来又将充分加热色球，以解释观测到的紫外线光谱是否起源于那里。它还将评估这一机制是否能够解释色球光谱观测。这需要四项相互关联的研究任务：(1)求解对流中性气体推动其越过磁力线时的等离子体漂移和场；(2)分析适用于在那里发现的碰撞等离子体的流动不稳定性理论；(3)进行一系列动力学模拟，以探索由此产生的湍流的非线性和热性质；以及(4)将产生的电子加热纳入辐射传输程序，以评估其对色球辐射的影响。这项研究结合了美国国家科学基金会/能源部在基础科学和工程学方面的伙伴关系所涵盖的几个研究领域。

The goal of this project is to provide a detailed verifiable explanation of the origin of the heating of the solar atmosphere. Most of the light reaching Earth originates at the 'surface' of the sun, a region called the photosphere. However, the regions of the solar atmosphere immediately above this surface, the solar chromosphere and corona, create most of the dangerous Ultraviolet (UV) and X-ray radiation. These regions also generate the solar wind, a stream of charged particles that pass the Earth at speeds in excess of 400km/s. Both the rapidly changing radiation and the solar wind create hazards for spacecraft, astronauts, and have a number of important terrestrial impacts. A long-standing mystery has prevented scientists from understanding and accurately modeling the chromosphere and corona. A short distance above the 'surface' of the sun, the solar atmosphere's temperature jumps up by a factor of two to three. The goal of this project is to provide an explanation of the origin of this heating. The project will also provide opportunities to recruit and train student researchers in plasma and solar physics, simulations, and modeling at the Boston University. Many of the Boston University PI's undergraduate research advisees, about half of whom are women, have continued on to graduate school. This research will examine whether solar plasma flows emerging from the photosphere can transfer sufficient energy into turbulent plasma of the solar atmosphere, which, in turn, will heat the chromosphere sufficiently to explain whether the observed UV spectra originate there. It will also evaluate whether this mechanism can account for chromospheric spectral observations. This requires four linked research tasks: (1) solving for plasma drifts and fields when a convecting neutral gas pushes it across magnetic field lines; (2) analyzing the theory of streaming instabilities applicable to the collisional plasma found there; (3) performing a series of kinetic simulations to explore the nonlinear and thermal properties of the resulting turbulence; and (4) incorporating the resulting electron heating into a radiative transport code in order to evaluate its impact on chromospheric radiance. This research combines several research areas encompassed by the NSF/DOE Partnership in Basic Science and Engineering.