Nanoflares: Explosive Heating of our Sun's Atmosphere

纳米耀斑：太阳大气的爆炸性加热

基本信息

批准号：
ST/L002744/1
负责人：
David Jess
金额：
$ 35.38万
依托单位：
Queen's University Belfast
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FL002744%2F1
关键词：
Nanoflares Explosive Heating our Sun

项目摘要

The Sun is one of the most important objects for humankind, with solar activity driving "space weather" and having a profound effect on the Earth's environment. We can directly see the effects of the Sun's powerful radiation through fascinating sights on Earth, such as the aurora borealis. However, it is the paradoxical nature of our Sun's temperature structure that continues to frustrate scientists. One of the greatest scientific problems plaguing physicists is the fact that the outer atmosphere of our Sun is much hotter than its surface. Common sense leads us to believe that the local temperature will decrease as we move away from the Sun's 6000 K surface temperature. However, the corona, an atmospheric layer a few thousand km above the surface, radiates with a temperature exceeding one million degrees. Efforts to understand the heating processes responsible have remained at the forefront of observational and theoretical research for over 50 years, producing a popular class of theory known as flare heating. This mechanism suggests that turbulent plasma processes cause the magnetic field lines embedded in the Sun's atmosphere to become twisted and stretched. The process of magnetic reconnection results in these strained field lines returning to a more stable configuration, but releasing huge quantities of energy in the process. A large-scale solar flare can release in excess of 10^25 Joules of energy during a single event; the equivalent of over 5 million times more than the total combined energy of all atomic bombs ever detonated. However, these large events are too rare to support the continuously elevated temperatures in our Sun's outer atmosphere. Instead, it is believed that small-scale flares, or "nanoflares" with an equivalent energy of a single modern atomic bomb, may occur with such regularity that they can provide a continuous basal background heating. It is my desire to help improve our understanding of the physical processes at work within the Sun's atmosphere, an object that is so influential to life on Earth. A natural consequence of understanding the effects of solar flares will be the ability to predict solar activity, something that will ultimately allow us to protect ourselves from fierce outbursts of space weather. To pursue this crucial agenda, we need to observe and model these explosive processes occurring in the Sun's atmosphere on their intrinsic scales. A new breed of highly sensitive scientific cameras will allow for the first time fundamental processes associated with the release of magnetic energy to be studied at an unprecedented level of detail. With an STFC Research Grant, a post-doctoral researcher will employ one of these modern pieces of equipment to image a variety of magnetic structures in the Sun's atmosphere with frame rates approaching 100 per second. The intensities of all structures will be monitored, with the characteristics of small-scale nanoflares evaluated. An in-depth examination of the regions where nanoflare activity is omnipresent will allow the processes at work to be compared precisely to the underlying magnetic field configurations. Fundamental parameters deduced from high-resolution observations will be incorporated into advanced computer simulations. Large computer clusters, often exceeding 200 CPUs, will be used to examine the effects of sub-resolution nanoflare activity on the intensity profiles extracted from the high-resolution observations. A direct comparison between the simulations and the observations will be undertaken, with key nanoflare characteristics determined, including the reconnection rates, the total energy released, and the plasma relaxation time scales. For the first time, the conditions promoting nanoflares will be understood, with the specific role they play in the heating of our Sun's atmosphere evaluated.

太阳是人类最重要的天体之一，太阳活动驱动“太空天气”，并对地球环境产生深远影响。我们可以通过地球上迷人的景象（例如北极光）直接看到太阳强大辐射的影响。然而，太阳温度结构的矛盾性质继续让科学家们感到沮丧。困扰物理学家的最大科学问题之一是太阳的外层大气比其表面热得多。常识让我们相信，当我们远离太阳 6000 K 的表面温度时，局部温度将会降低。然而，日冕是距地表数千公里的大气层，其辐射温度超过百万度。 50多年来，了解加热过程的努力一直处于观测和理论研究的前沿，产生了一种被称为火炬加热的流行理论。这种机制表明，湍流等离子体过程导致嵌入太阳大气中的磁力线变得扭曲和拉伸。磁重联过程导致这些应变磁力线恢复到更稳定的配置，但在此过程中释放了大量能量。大规模太阳耀斑在一次事件中可以释放超过 10^25 焦耳的能量；相当于所有曾经引爆的原子弹总能量的500万倍以上。然而，这些大型事件太罕见，无法支持太阳外层大气温度的持续升高。相反，人们相信，小规模耀斑或“纳米耀斑”的能量相当于单个现代原子弹的能量，可能会定期发生，从而提供连续的基础背景加热。我希望帮助提高我们对太阳大气层物理过程的理解，太阳大气层对地球上的生命影响如此之大。了解太阳耀斑影响的自然结果将是预测太阳活动的能力，这最终将使我们能够保护自己免受剧烈的太空天气爆发的影响。为了实现这一重要议程，我们需要在太阳大气中发生的这些爆炸过程的内在尺度上进行观察和建模。新型高灵敏度科学相机将首次以前所未有的细节水平研究与磁能释放相关的基本过程。凭借 STFC 研究补助金，一名博士后研究员将使用其中一台现代化设备对太阳大气中的各种磁结构进行成像，帧速率接近每秒 100 个。所有结构的强度都将受到监测，并评估小规模纳米耀斑的特征。对纳米耀斑活动无处不在的区域进行深入检查，将使工作过程与底层磁场配置进行精确比较。从高分辨率观测中推导出来的基本参数将被纳入先进的计算机模拟中。通常超过 200 个 CPU 的大型计算机集群将用于检查亚分辨率纳米耀斑活动对从高分辨率观测中提取的强度分布的影响。将进行模拟和观测之间的直接比较，并确定关键的纳米耀斑特征，包括重联率、释放的总能量和等离子体弛豫时间尺度。我们将首次了解促进纳米耀斑的条件，并评估它们在加热太阳大气中所发挥的具体作用。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

TRACING THE CHROMOSPHERIC AND CORONAL MAGNETIC FIELD WITH AIA, IRIS, IBIS, AND ROSA DATA

利用 AIA、IRIS、IBIS 和 ROSA 数据追踪色球层和日冕磁场

DOI：
http://dx.10.3847/0004-637x/826/1/61
发表时间：
2016
期刊：
The Astrophysical Journal
影响因子：
0
作者：
Aschwanden M
通讯作者：
Aschwanden M

An Inside Look at Sunspot Oscillations with Higher Azimuthal Wavenumbers

深入了解具有更高方位角波数的太阳黑子振荡

DOI：
10.3847/1538-4357/aa73d6
发表时间：
2017-05-17
期刊：
The Astrophysical Journal
影响因子：
0
作者：
D. Jess;T. Doorsselaere;G. Verth;V. Fedun;S. K. Prasad;R. Erdélyi;P. Keys;S. Grant;H. Uitenbroek;Damian J. Christian
通讯作者：
Damian J. Christian

Magnetohydrodynamic Nonlinearities in Sunspot Atmospheres: Chromospheric Detections of Intermediate Shocks

太阳黑子大气中的磁流体动力学非线性：中间激波的色层探测

DOI：
http://dx.10.3847/1538-4357/ab7a90
发表时间：
2020
期刊：
The Astrophysical Journal
影响因子：
0
作者：
Houston S
通讯作者：
Houston S

Statistical Signatures of Nanoflare Activity. II. A Nanoflare Explanation for Periodic Brightenings in Flare Stars observed by NGTS

纳米耀斑活动的统计特征。

DOI：
http://dx.10.48550/arxiv.2010.04167
发表时间：
2020
期刊：
影响因子：
0
作者：
Dillon C
通讯作者：
Dillon C

The Magnetic Response of the Solar Atmosphere to Umbral Flashes

太阳大气对本影闪光的磁响应

DOI：
10.3847/1538-4357/aab366
发表时间：
2018-02-28
期刊：
The Astrophysical Journal
影响因子：
0
作者：
S. J. Houston;D. Jess;A. A. Ramos;A. A. Ramos;S. Grant;C. Beck;Aimee A. Norton;S. Prasad
通讯作者：
S. Prasad