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Solar Wind Reconnection Exhausts in the Inner Heliosphere Observed by Helios and Detected via Machine Learning
The Astrophysical Journal ( IF 4.8 ) Pub Date : 2020-05-26 , DOI: 10.3847/1538-4357/ab8812
H. Tilquin 1 , J. P. Eastwood 1 , T. D. Phan 2
Affiliation  

Reconnecting current sheets in the solar wind play an important role in the dynamics of the heliosphere and offer an opportunity to study magnetic reconnection exhausts under a wide variety of inflow and magnetic shear conditions. However, progress in understanding reconnection can be frustrated by the difficulty of finding events in long time-series data. Here we describe a new method to detect magnetic reconnection events in the solar wind based on machine learning, and apply it to Helios data in the inner heliosphere. The method searches for known solar wind reconnection exhaust features, and parameters in the algorithm are optimized to maximize the Matthews Correlation Coefficient using a training set of events and non-events. Applied to the whole Helios data set, the trained algorithm generated a candidate set of events that were subsequently verified by hand, resulting in a database of 88 events. This approach offers a significant reduction in construction time for event databases compared to purely manual approaches. The database contains events covering a range of heliospheric distances from ~0.3 to ~1 au, and a wide variety of magnetic shear angles, but is limited by the relatively coarse time resolution of the Helios data. Analysis of these events suggests that proton heating by reconnection in the inner heliosphere depends on the available magnetic energy in a manner consistent with observations in other regimes such as at the Earth's magnetopause, suggesting this may be a universal feature of reconnection.

中文翻译:

Helios 观测并通过机器学习检测到的内日光层中的太阳风重联排气

重新连接太阳风中的电流片在日光层动力学中起着重要作用,并提供了研究在各种流入和磁剪切条件下磁重新连接排气的机会。然而,在长时间序列数据中查找事件的难度可能会阻碍理解重新连接的进展。在这里,我们描述了一种基于机器学习检测太阳风中磁重联事件的新方法,并将其应用于内日光层的 Helios 数据。该方法搜索已知的太阳风重连排气特征,并优化算法中的参数以使用事件和非事件的训练集最大化马修斯相关系数。应用于整个 Helios 数据集,经过训练的算法生成了一组候选事件,这些事件随后被手工验证,从而产生了一个包含 88 个事件的数据库。与纯手动方法相比,这种方法显着减少了事件数据库的构建时间。该数据库包含的事件涵盖从~0.3 到~1 au 的一系列日光层距离和各种磁剪切角,但受到 Helios 数据相对粗糙的时间分辨率的限制。对这些事件的分析表明,内日光层重联产生的质子加热取决于可用的磁能,其方式与在地球磁层顶等其他区域的观测结果一致,这表明这可能是重联的普遍特征。与纯手动方法相比,这种方法显着减少了事件数据库的构建时间。该数据库包含的事件涵盖从~0.3 到~1 au 的一系列日球层距离,以及各种各样的磁剪切角,但受到 Helios 数据相对粗糙的时间分辨率的限制。对这些事件的分析表明,内日光层重联产生的质子加热取决于可用的磁能,其方式与其他地区(例如地球磁层顶)的观测结果一致,这表明这可能是重联的普遍特征。与纯手动方法相比,这种方法显着减少了事件数据库的构建时间。该数据库包含的事件涵盖从~0.3 到~1 au 的一系列日球层距离,以及各种各样的磁剪切角,但受到 Helios 数据相对粗糙的时间分辨率的限制。对这些事件的分析表明,内日光层重联产生的质子加热取决于可用的磁能,其方式与其他地区(例如地球磁层顶)的观测结果一致,这表明这可能是重联的普遍特征。但受限于 Helios 数据相对粗糙的时间分辨率。对这些事件的分析表明,内日光层重联产生的质子加热取决于可用的磁能,其方式与其他地区(例如地球磁层顶)的观测结果一致,这表明这可能是重联的普遍特征。但受限于 Helios 数据相对粗糙的时间分辨率。对这些事件的分析表明,内日光层重联产生的质子加热取决于可用的磁能,其方式与其他地区(例如地球磁层顶)的观测结果一致,这表明这可能是重联的普遍特征。
更新日期:2020-05-26
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