arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2012.15406astro-ph.SRphysics.space-ph
收藏

太阳活动区平坦磁场中冷日冕的消失

The Missing Cool Corona in the Flat Magnetic Field around Solar Active Regions

Talwinder Singh, Alphonse C. Sterling, Ronald L. Moore

阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

SDO/AIA在几个EUV波段对整个太阳盘成像，每个波段对一个或多个特定温度的日冕等离子体发射敏感。我们观察到，当孤立的活动区域（AR）在磁盘上，在一些冠状EUV通道的全磁盘图像显示AR的外围作为一个黑暗的护城河周围的AR。在这里，我们提出了七个具体的例子，从时间段选择时，只有一个单一的AR存在于磁盘上。在视觉上，我们观察到壕沟在AIA 171埃带中最突出，其对来自等离子体的发射在log 10 T = 5.8处最敏感。通过检查从六个AIA EUV通道中发现的1D视线发射测量温度分布，我们发现对于大多数情况，护城河的强度在log 10 T ~ 5.7 - 6.2的温度范围内最低。我们认为，黑暗护城河的存在是因为从AR向外扩散的强大磁场的压力压在下面的磁环上，使这些磁环变平-以及AR在护城河上方的最低磁环-到低海拔。根据Antiochos & Noci（1986）的说法，这些环通常会发出大部分171埃的辐射，但它们被限制在地表以上的高度，这些高度太低，无法维持171埃的等离子体，而更热的EUV发射等离子体则维持在更高高度的长AR日冕环中。这可能解释了围绕AR的低日冕温度黑暗护城河。

英文摘要：

SDO/AIA images the full solar disk in several EUV bands that are each sensitive to coronal plasma emissions of one or more specific temperatures. We observe that when isolated active regions (ARs) are on the disk, full-disk images in some of the coronal EUV channels show the outskirts of the AR as a dark moat surrounding the AR. Here we present seven specific examples, selected from time periods when there was only a single AR present on the disk. Visually, we observe the moat to be most prominent in the AIA 171 Angstrom band, which has the most sensitivity to emission from plasma at log10 T = 5.8. By examining the 1D line-of-sight emission measure temperature distribution found from six AIA EUV channels, we find the intensity of the moat to be most depressed over the temperature range log10 T ~ 5.7 - 6.2 for most of the cases. We argue that the dark moat exists because the pressure from the strong magnetic field that splays out from the AR presses down on underlying magnetic loops, flattening those loops -- along with the lowest of the AR's own loops over the moat -- to a low altitude. Those loops, which would normally emit the bulk of the 171 Angstrom emission, are restricted to heights above the surface that are too low to have 171 Angstrom-emitting plasmas sustained in them, according to Antiochos & Noci (1986), while hotter EUV-emitting plasmas are sustained in the overlying higher-altitude long AR-rooted coronal loops. This potentially explains the low-coronal-temperature dark moats surrounding the ARs.

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。

↑