Collaborative Research: SHINE: Observational and Theoretical Studies of the Parametric Decay Instability in the Lower Solar Atmosphere

目前尚不清楚太阳外层日冕是如何被加热到数百万度的。一种可能的机制是通过参数衰变不稳定性(PDI)。该项目针对太阳、日球层和行星际环境(SIRE)的目标，通过数值模拟和分析天基和NSF资助的地面太阳观测来了解太阳日冕。该项目还支持纽约市和新墨西哥州的外联活动。两名博士后研究人员和哥伦比亚大学的本科生将得到支持。该项目将确定PDI是否是太阳大气中的一个重要过程。该团队将分析来自日冕多通道偏振仪、极端紫外线成像光谱仪、界面区域成像光谱仪和美国国家科学基金会资助的丹尼尔·K·井上太阳望远镜的观测结果。数值模拟将被用来更好地理解在过渡区和日冕的等离子体性质中存在梯度时的PDI行为。磁流体力学模拟将被用来研究低太阳大气中Alfven波和PDI的生长，在那里梯度的尺度长度小于波长。这对于理解密度波动是如何在离太阳非常近的地方产生的至关重要。此外，与PDI产生的声波相关的离子加热将使用混合模拟进行研究，以估计阿尔芬波能在较低大气中耗散的比例。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

It is unclear how the outer layer of the Sun, the corona, is heated to millions of degrees. One potential mechanism is through the parametric decay instability (PDI). This project addresses the Solar, Heliospheric, and Interplanetary Environment (SHINE) goal of understanding the solar corona through numerical simulations and analysis of space-based and NSF-funded ground based solar observations. The project also supports outreach activities in New York City and New Mexico. Two post-doctoral researchers will be supported, along with undergraduate students at Columbia University.The project will determine whether PDI is an important process in the solar atmosphere. The team will analyze observations from the Coronal Multichannel Polarimeter, the Extreme Ultraviolet Imaging Spectrometer, the Interface Region Imaging Spectrometer, and the NSF-funded Daniel K. Inouye Solar Telescope. Numerical modeling will be used to better understand the behavior of PDI in the presence of gradients in the plasma properties of the transition region and the corona. Magnetohydrodynamic simulations will be carried out to study Alfven waves and PDI growth in the lower solar atmosphere, where the scale length of gradients is smaller than the wavelength. This is critical to understand how density fluctuations are generated very close to the Sun. Moreover, ion heating associated with acoustic waves produced by PDI will be investigated using hybrid simulations, to estimate what fraction of the Alfven wave power can be dissipated in the lower atmosphere.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.