arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0906.4600astro-ph.SR
收藏

EIS/Hinode观测到的极冕洞阿尔芬波的特征

Signatures of Alfven waves in the polar coronal holes as seen by EIS/Hinode

D. Banerjee, D. Perez-Suarez, J. G. Doyle

摘要:

上下文我们诊断的性质的羽流和羽流间区域在极冕洞和波的作用,在加速的太阳风。目标。我们试图检测阿尔芬波是否存在于极冕洞通过EUV线宽的变化。方法.使用光谱观测在极冕洞区域与EIS光谱仪日出,我们研究的线宽和电子密度的变化作为高度的函数。我们使用了Fe xii 186.88 A & 195.119 A和Fe xiii 203.82 A & 202.04 A的密度敏感线对。结果对于极地地区,线宽数据表明,非热视线速度从26公里/秒,在1000以上的边缘增加到42公里/秒,约15000(即110,000公里)以上的边缘。在相同的距离上,电子密度从3:3 × 10^9 cm^-3下降到1:9 × 10^8 cm^-3。结论.这些结果意味着,非热速度是成反比的平方根的电子密度,在很好的协议与无阻尼径向传播的线性阿尔芬波的预测。我们的数据提供了在极冕洞区域的阿尔芬波的签名,这可能是重要的太阳风的加速。

英文摘要:

Context. We diagnose the properties of the plume and interplume regions in a polar coronal hole and the role of waves in the acceleration of the solar wind. Aims. We attempt to detect whether Alfven waves are present in the polar coronal holes through variations in EUV line widths. Methods. Using spectral observations performed over a polar coronal hole region with the EIS spectrometer on Hinode, we study the variation in the line width and electron density as a function of height. We use the density sensitive line pairs of Fe xii 186.88 A & 195.119 A and Fe xiii 203.82 A & 202.04 A . Results. For the polar region, the line width data show that the nonthermal line-of-sight velocity increases from 26 km/s at 1000 above the limb to 42 km/s some 15000 (i.e. 110,000 km) above the limb. The electron density shows a decrease from 3:3 10^9 cm^-3 to 1:9 10^8 cm^-3 over the same distance. Conclusions. These results imply that the nonthermal velocity is inversely proportional to the quadratic root of the electron density, in excellent agreement with what is predicted for undamped radially propagating linear Alfven waves. Our data provide signatures of Alfven waves in the polar coronal hole regions, which could be important for the acceleration of the solar wind.

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。

↑