Energetic Ions and Electrons in Solar Jets

恒星耀斑中离子和电子的加速在宇宙中是普遍存在的，然而，我们的太阳是唯一一个可以共同观察到高能粒子和它们的源耀斑的天体物理对象。太阳耀斑的加速机制极大地增强了3He和超重核（如197Au和207Pb）等稀有元素（高达1万倍），这一机制令人困惑了近50年，是天体物理学中最极端的分异例子之一。测量到的重离子加速随离子质量的增加而增加，但与低质量3He元素发生的最强增强相冲突，表明离子加速的机制不止一种。与逃逸的高能粒子有关的耀斑通常以喷流的形式被观察到，这意味着磁重联包括向行星际空间开放的磁场线。该项目旨在提高我们对太阳耀斑中离子增强机制的理解，首次解决高能离子和电子及其太阳源之间的联系。具体来说，该项目解决了1)在有共同离子和电子检测的事件中，与只有一种粒子成分占主导地位的源相比，太阳源有多大的不同，以及2)向行星际空间的注入/传输在多大程度上导致了缺乏离子或电子检测。目标1)将通过将射流结构和底层磁场的前所未有的高分辨率成像观测与高能离子和电子的原位观测特性相结合来解决。目标2)将通过将注入延迟（低能和高能电子之间以及电子和离子之间）与太阳源特性联系起来来解决。

Acceleration of ions and electrons in stellar flares is ubiquitous in the universe, however, our Sun is the only astrophysical object where energetic particles and their source flares can be jointly observed. The acceleration mechanism in solar flares, tremendously enhancing (up to factors of ten thousand) rare elements like 3He and ultra-heavy nuclei (like 197Au and 207Pb), has been puzzling for almost 50 years and presents one of the most extreme fractionation examples in astrophysics. The measured heavy-ion enhancement, increasing with ion mass, conflicts with the strongest enhancement which occurs for low-mass 3He element indicating that more than one mechanism is involved in the ion acceleration. Flares associated with escaping energetic particles have been commonly observed in jet-like forms, implying magnetic reconnection comprising field lines open to interplanetary space. This project aims to advance our understanding of the ion enhancement mechanisms operating in solar flares addressing for the first time the association between the energetic ions and electrons and their solar sources. Specifically, the project resolves 1) how different are solar sources in events with a common ion and electron detection compared to sources where only one particle component is dominant, and 2) to what extent is the injection/transport to/in interplanetary space responsible for lack of ion or electron detection. The objective 1) will be addressed by relating unprecedented high-resolution imaging observations of the jet structure and underlying magnetic fields with the in-situ observed properties of energetic ions and electrons. The objective 2) will be addressed by relating injection delays (between the low and high energy electrons and between electrons and ions) with solar source characteristics.