Estimating the Temperature and Density of a Spicule from 100 GHz Data Obtained with ALMA
Estimating the Temperature and Density of a Spicule from 100 GHz Data Obtained with ALMA
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DOI：
10.3847/2041-8213/ab62a5
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
M. Shimojo;T. Kawate;T. Okamoto;T. Yokoyama;N. Narukage;T. Sakao;K. Iwai;G. Fleishman;K. Shibata-K.-S
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作者：
M. Shimojo;T. Kawate;T. Okamoto;T. Yokoyama;N. Narukage;T. Sakao;K. Iwai;G. Fleishman;K. Shibata-K.-S
我们成功地利用太阳动力学天文台上的阿塔卡马大型毫米/亚毫米阵列（ALMA）、界面区域成像摄谱仪（IRIS）和大气成像组件（AIA）同时观测了两个大骨针。一种是 IRIS Mg ii 狭缝颌图像和 AIA 304 Å 图像中看到的针状体（Mg ii/304 Å 针状体）。另一种是用 ALMA 获得的 100 GHz 图像中看到的针状体（100 GHz 针状体）。尽管100 GHz针状体在早期阶段与Mg ii/304 Å针状体重叠，但在早期阶段后的IRIS Mg ii和AIA 304 Å图像中并未显示出任何相应的结构。这表明骨针是个体事件，没有物理关系。为了获得 100 GHz 骨针的物理参数，我们使用两种不同的方法估计光学深度作为温度和密度的函数。一种是通过假设填充因子来使用观测到的亮度温度，另一种是使用光学深度的发射模型。比较结果表明，100 GHz 针状体中等离子体的动力学温度和电离氢的数密度分别为 ∼6800 K 和 2.2 × 1010 cm−3。估计值可以解释 193 Å 图像中的吸收结构，该图像显示为 100 GHz 针状体的对应物。这些结果表明，本信中提出的 100 GHz 针状体在以前的术语中被归类为没有热鞘的大针状体。
We succeeded in observing two large spicules simultaneously with the Atacama Large Millimeter/submillimeter Array (ALMA), the Interface Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. One is a spicule seen in the IRIS Mg ii slit-jaw images and AIA 304 Å images (Mg ii/304 Å spicule). The other one is a spicule seen in the 100 GHz images obtained with ALMA (100 GHz spicule). Although the 100 GHz spicule overlapped with the Mg ii/304 Å spicule in the early phase, it did not show any corresponding structures in the IRIS Mg ii and AIA 304 Å images after the early phase. It suggests that the spicules are individual events and do not have a physical relationship. To obtain the physical parameters of the 100 GHz spicule, we estimate the optical depths as a function of temperature and density using two different methods. One is using the observed brightness temperature by assuming a filling factor, and the other is using an emission model for the optical depth. As a result of comparing them, the kinetic temperature of the plasma and the number density of ionized hydrogen in the 100 GHz spicule are ∼6800 K and 2.2 × 1010 cm−3. The estimated values can explain the absorbing structure in the 193 Å image, which appear as a counterpart of the 100 GHz spicule. These results suggest that the 100 GHz spicule presented in this Letter is classified to a macrospicule without a hot sheath in former terminology.