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arXiv 2203.03529astro-ph.SR
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用IRIS和SDO对瞬变热和冷环的光谱和成像观测

Spectroscopic and imaging observations of transient hot and cool loops by IRIS and SDO

Girjesh R. Gupta, Sushree S. Nayak

摘要:

日冕环是太阳大气的基本组成部分,可以在各种长度尺度上观测到。但其形成机制尚不清楚。在本文中,我们提出的光谱和成像观测的小尺度瞬变和随后形成的瞬态循环。为此,我们利用了AIA和IRIS-SJI记录的多波长观测,以及IRIS提供的光谱测量。对于光球磁场数据,我们获得了HMI提供的视线磁图数据。同时观察到小规模的瞬态与几个EUV和UV通带的AIA和IRIS-SJI。HMI磁图提供了这些瞬变下负通量抵消的证据。差分发射测量(DEM)分析表明,瞬态达到的温度高达8 MK,而另一个只达到0.4 MK。这些瞬态进一步导致形成具有相似温度分布的小尺度回路,因此分别称为热回路和冷回路。在事件发生的过程中,IRIS狭缝对该区域进行光栅扫描,从而提供了瞬态和相关环路的光谱测量。这使我们能够对热回路和冷回路进行深入研究。利用密度敏感的O-IV线对,我们得到了沿热环和冷环的平均电子密度分别为$10^{11.2}$和$10^{10.8}$ cm $^{-3}$。能量估计表明,磁通抵消可以很容易地为热瞬态供电,而不足以为冷瞬态供电。寿命估计和磁场外推表明存在小规模和精细结构内这些循环。结果提供了至关重要的成分的物理回路的形成和相关的热力学。

英文摘要:

Coronal loops are basic building blocks of solar atmosphere and are observed on various length scales. However, their formation mechanism is still unclear. In this paper, we present the spectroscopic and imaging observations of small-scale transients and subsequent formation of transient loops. For the purpose, we have utilized the multi-wavelength observations recorded by AIA and IRIS-SJI, along with spectroscopic measurements provided by IRIS. For the photospheric magnetic field data, we obtained line-of-sight magnetogram data provided by HMI. Small-scale transients are simultaneously observed with several EUV and UV passbands of AIA and IRIS-SJI. HMI magnetogram provides evidence of negative flux cancellations beneath these transients. Differential Emission Measure (DEM) analysis shows that one of the transient attains temperature up to 8 MK whereas another one reaches only up to 0.4 MK. These transients further lead to the formation of small-scale loops with similar temperature distributions, and thus termed as hot and cool loops respectively. During the course of events, IRIS slit was rastering the region and thus provided spectroscopic measurements at both transients and associated loops. This enabled us to perform in-depth investigations of hot and cool loops. Using density sensitive O IV line pair, we obtained average electron densities along the hot and cool loop to be $10^{11.2}$ and $10^{10.8}$ cm$^{-3}$ respectively. Energy estimates suggest that flux cancellation can easily power the hot transient whereas is insufficient for cool transient. Life time estimates and magnetic field extrapolation suggest presence of small-scale and fine structures within these loops. Results provide crucial ingredients on the physics of loop formation and involved thermodynamics.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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