We have observed a total of five UVCS/SOHO polar jets that correlate with the Extreme-Ultraviolet Imaging Telescope (EIT) and Large Angle Spectrometric Coronagraph (LASCO) jet events. We analyzed spectroscopic observations of these jets and found that they typically undergo two phases: at the first phase the O Ⅵ lines show a brief intensity enhancement (by a factor of 1.4) and narrowing (by a factor of 0.8), while the H Ⅰ Lyα line is not enhanced, and the second phase, about 25 minutes later, when the H Ⅰ Lyα line shows an intensity enhancement (by a factor of 1.3) and narrowing (by a factor of 0.8), while the O Ⅵ line is relatively unchanged. We modeled the observable properties of the jets from 1997 August 5, detected at 1.71 solar radius. We interpret the first phase as the fast, dense centroid of the jet passing by the UVCS slit. The empirical jet model was able to reproduce the observed line properties with electron density enhancement by a factor of 3.2 (with a resulting density of 4.5 x 10~6 cm~(-3)), an electron temperature decrease (change by a factor of 0.50 to 750,000 K), and the centroid outflow velocity larger than 280 km s~(-1). During the second phase, the model required a further decrease in the electron temperature (change by a factor of 0.10, with a jet temperature of only 150,000 K), along with a weaker electron density (1.7 x 10~6 cm~(-3)) and an outflow velocity of 205 km s~(-1). Possible scenarios of the electron temperature variations needed to account for observed conditions on 1997 August 5 indicate that some heating is required. We computed models of the temperature and nonequilibrium ionization state of an expanding plasma using various forms for the heating rates. We found that the jet had to leave the Sun at an electron temperature below 2.5 x 10~6 K and that a heating rate of the same order as the average coronal hole heating is required. Such low initial temperatures are consistent with the idea that the jets observed by LASCO, EIT, and UVCS are different than previously observed coronal X-ray jets.
展开▼
机译：我们已经观察到总共五次UVCS / SOHO极射流，它们与极紫外成像望远镜（EIT）和大角度光谱日冕仪（LASCO）射流相关。我们分析了这些射流的光谱观察结果，发现它们通常经历两个阶段：在第一阶段，OⅥ线显示出短暂的强度增强（1.4倍）和变窄（0.8倍），而HⅠ Lyα谱线没有增强，大约25分钟后的第二阶段，HⅠLyα谱线显示出强度增强（1.3倍）和变窄（0.8倍），而OⅥ谱线相对较弱。不变。我们对从1997年8月5日起在太阳半径1.71处检测到的喷流的可观测特性建模。我们将第一阶段解释为通过UVCS狭缝的射流的快速，密集的质心。经验射流模型能够重现观察到的线特性，其中电子密度提高了3.2倍（结果密度为4.5 x 10〜6 cm〜（-3）），电子温度降低了（变化了0.3倍）。 0.50至750,000 K），质心流出速度大于280 km s〜（-1）。在第二阶段，该模型要求电子温度进一步降低（变化0.10倍，射流温度仅为150,000 K），并且电子密度较低（1.7 x 10〜6 cm〜（-3） ）），流出速度为205 km s〜（-1）。考虑到1997年8月5日观测到的条件所需的电子温度变化的可能情况表明需要进行一些加热。我们使用各种形式的加热速率计算了膨胀等离子体的温度和非平衡电离状态的模型。我们发现，射流必须以低于2.5 x 10〜6 K的电子温度离开太阳，并且需要与平均日冕孔加热相同数量级的加热速率。如此低的初始温度与LASCO，EIT和UVCS观测到的射流与先前观测到的日冕X射线射流不同的想法是一致的。
展开▼
