Magnetic Connectivity of the Ecliptic Plane within 0.5 au: Potential Field Source Surface Modeling of the First Parker Solar Probe Encounter
Magnetic Connectivity of the Ecliptic Plane within 0.5 au: Potential Field Source Surface Modeling of the First Parker Solar Probe Encounter
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DOI：
10.3847/1538-4365/ab4da7
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发表时间：
2020-02-01
影响因子：
8.7
通讯作者：
Whittlesey, Phyllis L.
中科院分区：
文献类型：
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作者：
Badman, Samuel T.;Bale, Stuart D.;Whittlesey, Phyllis L.
我们比较了帕克太阳探测器（PSP）上的FIELDS仪器在第一次与太阳相遇时的磁场测量结果与由势场源表面（PFSS）模型得到的预测结果。弹道传播用于将航天器连接到源表面。尽管模型很简单，但我们的结果与PSP对日球层磁场的首次观测结果惊人地吻合，从0.5 au （107.5 r -圆点）到0.16 au （35.7 r -圆点）。此外，我们表明，通过允许模型的光球输入随时间变化，以及通过使用原位PSP/太阳风电子α和质子测量太阳风速度而不是假设其随经纬度不变，将场从PSP向下平流到PFSS模型域，从而提高了协议的鲁棒性。我们还研究了PFSS模型的源面高度参数（R-SS），发现极低的源面高度（1.3-1.5 r圆点）预测了观测到的小尺度极性反转，否则会被常规建模参数冲掉。最后，我们从这些模型中提取场线轨迹。通过将这些图像叠加在极紫外图像上，我们观察到各种赤道和中纬度日冕洞的磁连性，表明了可能的磁足点，并为未来讨论PSP测量的太阳风来源提供了背景。
We compare magnetic field measurements taken by the FIELDS instrument on board Parker Solar Probe (PSP) during its first solar encounter to predictions obtained by potential field source surface (PFSS) modeling. Ballistic propagation is used to connect the spacecraft to the source surface. Despite the simplicity of the model, our results show striking agreement with PSP's first observations of the heliospheric magnetic field from similar to 0.5 au (107.5 R-circle dot) down to 0.16 au (35.7 R-circle dot). Further, we show the robustness of the agreement is improved both by allowing the photospheric input to the model to vary in time, and by advecting the field from PSP down to the PFSS model domain using in situ PSP/Solar Wind Electrons Alphas and Protons measurements of the solar wind speed instead of assuming it to be constant with longitude and latitude. We also explore the source surface height parameter (R-SS) to the PFSS model, finding that an extraordinarily low source surface height (1.3-1.5 R-circle dot) predicts observed small-scale polarity inversions, which are otherwise washed out with regular modeling parameters. Finally, we extract field line traces from these models. By overlaying these on extreme ultraviolet images we observe magnetic connectivity to various equatorial and mid-latitude coronal holes, indicating plausible magnetic footpoints and offering context for future discussions of sources of the solar wind measured by PSP.