Electron Temperatures of the Corona above a Solar Active Region Determined from S XV Spectra
Electron Temperatures of the Corona above a Solar Active Region Determined from S XV Spectra
复制标题
根据 S XV 光谱确定太阳活动区域上方日冕的电子温度
DOI：
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发表时间：
1997
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通讯作者：
Tetsuya Watanabe
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作者：
A. Sterling;H. Hudson;Tetsuya Watanabe
我们使用Yohkoh卫星上的Bragg晶体光谱仪（BCS）首次对活动区域上方的日冕进行了高分辨率软x射线光谱观测。我们观测到NOAA AR 7978，因为它在太阳边缘之外旋转，所以该地区的下部被遮蔽了。该区域在几天后完全消失后的时间内的长期整合显示出s15的大量可变背景。由于背景光谱是无特征的，所以掩星时间得到的谱线一定来自活动区域的上日冕。我们的结果支持了先前的发现，即活动区域的日冕由两个部分组成：一个是Te≈3 MK的较冷的稳定部分，另一个是温度超过5 MK的较热的瞬态部分。在微耀斑活动时间之外，日冕上等离子体的活跃区相对较少或没有，其Te < 3.5 MK。有证据表明，冷成分的Te随高度的增加而降低。
We present the first high-resolution soft X-ray spectral observations of the corona above an active region, using the Bragg crystal spectrometer (BCS) on board the Yohkoh satellite. We observed NOAA AR 7978 as it rotated beyond the solar limb so that the lower portions of the region were occulted. Long integrations from times after the region had totally disappeared some days later show a substantial, variable background in S XV. Since the background spectrum is featureless, spectral lines obtained from the time of occultation must originate from the upper corona of the active region. Our results support previous findings that the active region corona consists of two components: a cooler, steady component with Te ≈ 3 MK and a hotter, transient component in excess of 5 MK. This hotter component is due to microflares; outside the time of microflares there is relatively little or no active region upper coronal plasma with Te ≳ 3.5 MK. There is evidence for a decrease in Te with height for the cool component.