Modelling and Multi-wavelength Observations of Solar Flare Heating

太阳耀斑加热的建模和多波长观测

• 批准号: ST/N004981/2
• 负责人: Ryan Milligan
• 金额: $ 31.39万
• 依托单位: Queen's University Belfast
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FN004981%2F2
• 关键词: Modelling; Multi; wavelength; Observations; Solar

Our Sun is perceived to be a fairly benevolent star, bathing our planet in live-giving heat and light. But every 11 years or so, its behaviour changes, from quiescent to turbulent and back again. During periods of increased activity the Sun's twisted and contorted magnetic field continually undergoes episodes of complex reconfiguration to liberate vast quantities of pent-up energy. This energy goes into heating the solar plasma to temperatures of tens of millions of degrees and accelerating particles to near-relativistic velocities. Precisely how this energy conversation takes place remains an open question, and I aim to tackle this problem over the course of this Fellowship by capitalising upon the most advanced theoretical models and observational datasets currently available.Modern society is becoming increasingly dependent upon evermore advanced technologies. These systems, such as satellite communication, national power grids, and the Global Positioning System (GPS), are all susceptible to changes in the Sun's behaviour; more commonly referred to as space weather. Space weather typically comprises two phenomena: solar flares and coronal mass ejections (CMEs). CMEs are clouds of charged particles ejected off the Sun at millions of miles per hour, reaching the Earth in 2-3 days, where they can interfere with electrical systems and generate spectacular aurora, while solar flares are intense bursts of radiation that span the entire electromagnetic spectrum from radio waves to gamma-rays. This radiation traverses the Sun-Earth distance in just 8 minutes, and the ultraviolet (UV) component is known to change the composition and dynamics of our atmosphere. This can affect the motion of satellites in low Earth orbit, disrupt long-wave radio communication, and affect the transmission of GPS signals.During solar flares, much of the UV radiation is emitted by the chromosphere; a dense layer between the Sun's visible photosphere and the tenuous outer corona. The chromosphere is also where the bulk of a flare's energy emanates during its initial stages, and is the origin of material that occupies the overlying coronal loops. However, the mechanism by which the released energy gets transferred to the lower solar atmosphere remains elusive. It is commonly assumed that the delivery mechanism is a beam of high-energy electrons, and yet these particles are unable to penetrate to the depths at which the most energetic emission is believed to originate. Other proposed processes include heat conduction, relativistic ions, magnetic waves, or radiative backwarming. Fortunately, much of the radiation emitted contains a wealth of diagnostic information with which to probe the heated plasma. This allows us to distinguish between various heating mechanisms by measuring changes in temperature, density, velocity, etc, and comparing them to the predictions of theory.While solar flares may emit radiation across the entire spectrum, our spectral coverage is somewhat lacking in parts. Most remote sensing instruments - both in space and on the ground - are often designed to look at a very limited wavelength range. Therefore in order to build a more complete picture of the flaring solar atmosphere, coordinated observations between different instruments are crucial. A core goal of this research is therefore to search for and catalog flaring events observed by a variety of instruments simultaneously, as well as planning future coordinated observing campaigns. For parts of the spectrum that are not yet observable, outputs from numerical simulations shall be used to fill in the gaps. This will help to prepare for instrumentation that will come online during the course of the project. Similarly, there are regions of stellar flare spectra that are unobservable due to absorption by the interstellar medium. The outcomes of this research shall assist in characterising this emission on other stars, especially that which can affect exoplanet atmospheres.

我们的太阳被认为是一颗相当仁慈的星星，沐浴着我们的星球，给予生命的热和光。但每隔11年左右，它的行为就会发生变化，从平静到动荡，再回到平静。在活动增加的时期，太阳的扭曲和扭曲的磁场不断经历复杂的重新配置，以释放大量被压抑的能量。这些能量将太阳等离子体加热到数千万度的温度，并将粒子加速到接近相对论的速度。这种能量转换究竟是如何发生的仍然是一个悬而未决的问题，我的目标是通过利用目前最先进的理论模型和观测数据来解决这个问题。现代社会越来越依赖于越来越先进的技术。这些系统，如卫星通信、国家电网和全球定位系统（GPS），都容易受到太阳活动变化的影响;更常见的是空间天气。空间天气通常包括两种现象：太阳耀斑和日冕物质抛射（CME）。CME是以每小时数百万英里的速度从太阳喷射出的带电粒子云，在2-3天内到达地球，在那里它们可以干扰电气系统并产生壮观的极光，而太阳耀斑是强烈的辐射爆发，跨越从无线电波到伽马射线的整个电磁频谱。这种辐射在短短8分钟内穿过太阳-地球距离，紫外线（UV）成分已知会改变我们大气的组成和动力学。这会影响低地球轨道卫星的运动，扰乱长波无线电通信，并影响GPS信号的传输。在太阳耀斑期间，大部分紫外线辐射是由色球层发射的;太阳可见光球层和脆弱的外日冕之间的致密层。色球层也是耀斑初始阶段大部分能量散发的地方，也是占据日冕环的物质的来源。然而，释放的能量转移到低层太阳大气的机制仍然难以捉摸。人们通常认为，传输机制是一束高能电子，但这些粒子无法穿透到最具能量的发射被认为是起源的深度。其他提出的过程包括热传导，相对论离子，磁波，或辐射回暖。幸运的是，发射的大部分辐射包含了丰富的诊断信息，可以用来探测加热的等离子体。这使我们能够通过测量温度、密度、速度等的变化来区分各种加热机制，并将它们与理论预测进行比较。虽然太阳耀斑可能会在整个光谱范围内发射辐射，但我们的光谱覆盖范围有些不足。大多数遥感仪器-无论是在空间还是在地面上-往往被设计成只能观察非常有限的波长范围。因此，为了更全面地了解太阳大气层的燃烧情况，不同仪器之间的协调观测至关重要。因此，这项研究的核心目标是搜索和编目耀斑事件同时观察到的各种仪器，以及规划未来的协调观测活动。对于尚无法观察到的频谱部分，应使用数值模拟的输出来填补空白。这将有助于为项目过程中将上线的仪器做好准备。类似地，由于星际介质的吸收，恒星耀斑光谱中有一些区域是无法观测到的。这项研究的结果将有助于描述其他恒星的这种发射，特别是那些可能影响系外行星大气层的发射。

项目成果

Flare-induced Photospheric Velocity Diagnostics

• DOI: 10.3847/1538-4357/abfda8
• 发表时间: 2021-05
• 期刊: The Astrophysical Journal
• 作者: A. J. Monson;M. Mathioudakis;A. Reid;R. Milligan;D. Kuridze

Formation of the Lyman Continuum during Solar Flares

太阳耀斑期间莱曼连续体的形成

• DOI: 10.3847/1538-4357/acaf66
• 发表时间: 2023
• 期刊: The Astrophysical Journal
• 作者: McLaughlin S

Spicules in IRIS Mg ii Observations: Automated Identification

• DOI: 10.3847/1538-4357/acbe3f
• 发表时间: 2022-12
• 期刊: The Astrophysical Journal
• 作者: Vicki Herde;P. Chamberlin;D. Schmit;S. Bose;A. Daw;R. Milligan;V. Polito

Flare-induced Sunquake Signatures in the Ultraviolet as Observed by the Atmospheric Imaging Assembly

大气成像装置观测到的紫外线中耀斑诱发的日震特征

• DOI: 10.3847/1538-4357/ac0139
• 发表时间: 2021
• 期刊: The Astrophysical Journal
• 作者: Quinn S

The high-energy Sun - probing the origins of particle acceleration on our nearest star

高能太阳 - 探索离我们最近的恒星上粒子加速的起源

• DOI: 10.1007/s10686-021-09798-6
• 发表时间: 2021
• 期刊: Experimental Astronomy
• 影响因子: 3
• 作者: Matthews S