Decomposing the AIA 304 Å Channel into Its Cool and Hot Components

IF 2.7 3区 物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS
Patrick Antolin, Frédéric Auchère, Ethan Winch, Elie Soubrié, Ramón Oliver
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引用次数: 0

Abstract

The AIA 304 Å channel on board the Solar Dynamics Observatory (SDO) offers a unique view of \(\approx 10^{5}\text{ K}\) plasma emitting in the He ii 304 Å line. However, when observing off-limb, the emission of the (small) cool structures in the solar atmosphere (such as spicules, coronal rain and prominence material) can be of the same order as the surrounding hot coronal emission from other spectral lines included in the 304 Å passband, particularly over active regions. In this paper, we investigate three methods based on temperature and morphology that are able to distinguish the cool and hot emission within the 304 Å passband. The methods are based on the Differential Emission Measure (DEM), a linear decomposition of the AIA response functions (RFit) and the Blind Source Separation (BSS) technique. All three methods are found to produce satisfactory results in both quiescent and flaring conditions, largely removing the diffuse corona and leading to images with cool material off-limb in sharp contrast with the background. We compare our results with co-aligned data from the Interface Region Imaging Spectrograph (IRIS) in the SJI 1400 Å and 2796 Å channels, and find the RFit method to best match the quantity and evolution of the cool material detected with IRIS. Some differences can appear due to plasma emitting in the \(\log T=5.1\,\text{--}\,5.5\) temperature range, particularly during the catastrophic cooling stage prior to rain appearance during flares. These methods are, in principle, applicable to any passband from any instrument suffering from similar cool and hot emission ambiguity, as long as there is good coverage of the high-temperature range.

Abstract Image

将 AIA 304 Å 沟道分解为冷成分和热成分
太阳动力学天文台(SDO)上的 AIA 304 Å 频道为观测 He ii 304 Å 线发射的等离子体提供了独特的视角。然而,在离圈观测时,太阳大气中(小)冷结构(如尖晶石、日冕雨和突出物质)的发射可能与周围来自 304 Å 通带中其他光谱线的热日冕发射处于同一量级,尤其是在活跃区上空。在本文中,我们研究了三种基于温度和形态的方法,它们能够区分 304 Å 通带内的冷发射和热发射。这三种方法分别基于差分发射测量(DEM)、AIA 响应函数(RFit)的线性分解和盲源分离(BSS)技术。在静态和耀斑条件下,这三种方法都能产生令人满意的结果,在很大程度上消除了漫射日冕,使图像中的冷物质与背景形成鲜明对比。我们将我们的结果与界面区域成像光谱仪(IRIS)在 SJI 1400 Å 和 2796 Å 频道的共同对齐数据进行了比较,发现 RFit 方法与 IRIS 检测到的冷物质的数量和演变最为匹配。由于等离子体在(log T=5.1,text{--}\,5.5)温度范围内发射,特别是在耀斑期间雨出现之前的灾难性冷却阶段,可能会出现一些差异。这些方法原则上适用于任何仪器的任何通带,只要能很好地覆盖高温范围,这些仪器都会出现类似的冷热发射模糊现象。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Solar Physics
Solar Physics 地学天文-天文与天体物理
CiteScore
5.10
自引率
17.90%
发文量
146
审稿时长
1 months
期刊介绍: Solar Physics was founded in 1967 and is the principal journal for the publication of the results of fundamental research on the Sun. The journal treats all aspects of solar physics, ranging from the internal structure of the Sun and its evolution to the outer corona and solar wind in interplanetary space. Papers on solar-terrestrial physics and on stellar research are also published when their results have a direct bearing on our understanding of the Sun.
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