标题： 2008年3月SOHO/UVCS观测到的冠状伪流和双极流 显示英文标题

标题： Coronal Pseudo-Streamer and Bipolar Streamer Observed by SOHO/UVCS in March 2008

摘要： 上一个太阳活动极小期的特点是具有几个独特的方面，并且伴随着复杂的磁拓扑结构，其中存在两种不同类型的日冕流：伪流和双极流。 伪流或单极流是日冕结构，它们分离了相同磁极性的日冕洞，而在外日冕中没有电流片；与分离相反磁极性日冕洞的双极流不同。 在这项研究中，通过应用光球磁场测量的位势场源面外推法，在卡林顿旋转周期2067期间识别出了这两种结构的两个例子。 我们展示了伪流和双极流的光谱分析，这些结构在2008年3月12日至17日期间由太阳和日球天文台（SOHO）上的紫外日冕光谱仪（UVCS；Kohl等人，1995年）以高光谱和空间分辨率观测到。 通过分析O VI双线和Ly α线光谱，推断出扩展日冕中的太阳风等离子体参数，如动能温度、电子密度和流出速度（从1.7到2.1个太阳半径）。 考虑到了日冕的磁拓扑结构，并通过全球日冕的三维磁流体力学模型进行了外推。 分析结果显示了伪流物理参数的一些独特之处，与双极流相比：特别是，我们发现O VI离子的动能温度更高，流出速度更快，而电子密度值更低。 总之，我们指出伪流产生了一种“混合”类型的流出，介于慢速和快速太阳风之间，并且在非偶极太阳磁场配置下，它们可能是慢速/快速风的可能来源。 显示英文摘要

摘要： The last solar minimum is characterized by several peculiar aspects and by the presence of a complex magnetic topology with two different kinds of coronal streamers: pseudo-streamers and bipolar streamers. Pseudo-streamers or unipolar streamer are coronal structures which separate coronal holes of the same polarity, without a current sheet in the outer corona; unlike bipolar streamer that separate coronal holes of opposite magnetic polarity. In this study, two examples of these structures have been identified in the period of Carrington rotation 2067, by applying a potential-field source-surface extrapolation of the photospheric field measurements. We present a spectroscopic analysis of a pseudo-streamer and a bipolar streamer observed in the period 12-17 March 2008 at high spectral and spatial resolution by the Ultraviolet Coronagraph Spectrometer (UVCS; Kohl et al., 1995) onboard Solar and Heliospheric Observatory (SOHO). The solar wind plasma parameters, such as kinetic temperature, electron density and outflow velocity, are inferred in the extended corona (from 1.7 to 2.1 Rsun) analysing the O VI doublet and Ly alpha line spectra. The coronal magnetic topology is taken into account and has been extrapolated by a 3D magneto-hydrodynamic model of the global corona. The results of the analysis show some peculiarities of the pseudo-streamer physical parameters in comparison with those obtained for bipolar streamers: in particular, we have found higher kinetic temperature and higher outflow velocities of O VI ions and lower electron density values. In conclusion, we point out that pseudo-streamers produce a "hybrid" type of outflow that is intermediate between slow and fast solar wind and they are a possible source of slow/fast wind in not dipolar solar magnetic field configuration.