论文标题
在0.2和1 AU时观察到的冠状质量弹出：2019年4月1日至2日的事件
Coronal mass ejections observed by heliospheric imagers at 0.2 and 1 au: the events on April 1 and 2, 2019
论文作者
论文摘要
语境。我们研究了Parker Solar Probe（WISPR-I）的内部宽场成像仪在2019年4月1日至2日之间观察到的两个冠状质量弹出（CME）和板立体A的内层成像仪（HI-1）。这是从相似方向上的两个观点对CME观察结果进行的首次研究，但太阳距离截然不同。目标。我们的目标是了解PSP观察结果如何影响CME运动学，尤其是由于它靠近太阳。方法。我们使用来自两个航天器的成像观测值以及一组将CME视为点结构的分析表达式估算了CME位置，速度，加速度，传播方向和纵向偏转，并考虑了航天器位置的快速变化。结果。我们发现两个CME都很慢（$ <400 \ km \ s^{ - 1} $），在太阳 - 地球线的东传播。第二个CME似乎在$ \ sim 0.1 $到$ \ sim 0.2 \ au $之间加速，并以与太阳能旋转速度一致的角度向西偏转。我们发现CME太阳能距离（最高$ 0.05 \ au $，尤其是CME \＃1），Latitude（最高$ \ sim10^{\ circ} $）和经度（最高$ 24^{\ circ circ} $）时，发现了一些差异。结论。经度的差异可能是由于视觉上跟踪的特征而不是仪器偏见或适合假设所致。出于类似的原因，从WISPR-I观测值中得出的CME \＃1太阳能距离大于HI-1结果，而与所考虑的拟合参数无关。 CME运动学的错误估计值没有显示与观察器仪器相关的任何明确趋势。源区域的位置以及缺乏任何清晰的原位对应物（无论是在近地和PSP处）支持我们对这两个事件的传播方向的估计。
Context. We study two coronal mass ejections (CMEs) observed between April 1-2, 2019 by both the inner Wide-Field Imager for Parker Solar Probe (WISPR-I) and the inner heliospheric imager (HI-1) on board STEREO-A. This is the first study of CME observations from two viewpoints in similar directions but at considerably different solar distances. Aims. Our objective is to understand how the PSP observations affect the CME kinematics, especially due to its proximity to the Sun. Methods. We estimate the CME positions, speeds, accelerations, propagation directions and longitudinal deflections using imaging observations from two spacecraft, and a set of analytical expressions that consider the CME as a point structure and take into account the rapid change in spacecraft position. Results. We find that both CMEs are slow ($< 400\ km\ s^{-1}$), propagating eastward of the Sun-Earth line. The second CME seems to accelerate between $\sim 0.1$ to $\sim 0.2\ au$ and deflect westward with an angular speed consistent with the solar rotation speed. We find some discrepancies in the CME solar distance (up to $0.05\ au$, particularly for CME \#1), latitude (up to $\sim10^{\circ}$) and longitude (up to $24^{\circ}$) when comparing results from different fit cases (different observations or set of free parameters). Conclusions. Discrepancies in longitude are likely due to the feature tracked visually rather than instrumental biases or fit assumptions. For similar reasons, the CME \#1 solar distance, as derived from WISPR-I observations, is larger than the HI-1 result, regardless of the fit parameters considered. Error estimates for CME kinematics do not show any clear trend associated to the observing instrument. The source region location and the lack of any clear in situ counterparts (both at near-Earth and at PSP) support our estimate of the propagation direction for both events.
