Solar-wind predictions for the Parker Solar Probe orbit
Solar-wind predictions for the Parker Solar Probe orbit
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帕克太阳探测器轨道的太阳风预测
DOI：
10.1051/0004-6361/201731831
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
M. Venzmer
中科院分区：
文献类型：
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作者：
V. Bothmer;M. Venzmer
这项研究的范围是为帕克太阳探测器在2018 - 2025年的使命阶段前所未有的距离降低到9.86 Rs的太阳风环境建模。这项研究是在CGAUSS项目中进行的，该项目是德国对PSP使命的贡献，是PSP上WISPR成像仪的一部分。我们提出了一个经验的太阳风模型的内日球层，这是来自OMNI和Helios的数据。太阳黑子数（SSN）及其预测被用来推导太阳风参数对太阳活动的依赖关系，并为PSP使命进行预测。考虑到速度分布的双分量形状，用对数正态函数表示太阳风关键参数磁场强度、质子速度、密度和温度的频率分布。使用OMNI数据和来自两个Helios探测器的数据编译SSN的函数关系，参数的频率分布相对于太阳距离进行拟合。因此，一个经验的太阳风模型的内日光层，占太阳活动和太阳距离。列入SSN的预测和外推到PSP的近日点区域，使我们能够估计PSP的计划轨迹在其使命持续时间的太阳风环境。该经验模型估计了PSP在2018年第一近日点的太阳风值，0.16 Au：87 nT，340 km s-1，214 cm-3和503000 K。PSP的第一个最近近日点，发生在2024年的0.046 Au，估计为943 nT，290 km s-1，2951 cm-3和1930000 K。由于与现有观测相比，低于约20 Rs的模拟速度和温度值似乎被高估，这表明PSP将按计划直接测量低于20 Rs的太阳风加速和加热过程。
The scope of this study is to model the solar-wind environment for the Parker Solar Probe's unprecedented distances down to 9.86 Rs in its mission phase during 2018-2025. The study is performed within the CGAUSS project which is the German contribution to the PSP mission as part of the WISPR imager on PSP. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The sunspot number (SSN) and its predictions are used to derive dependencies of solar-wind parameters on solar activity and to forecast them for the PSP mission. The frequency distributions for the solar-wind key parameters magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions, considering the velocity distribution's bi-componental shape. Functional relations to the SSN are compiled using OMNI data and based on data from both Helios probes, the parameters' frequency distributions are fitted with respect to solar distance. Thus, an empirical solar-wind model for the inner heliosphere is derived, accounting for solar activity and solar distance. The inclusion of SSN predictions and the extrapolation down to PSP's perihelion region enables us to estimate the solar-wind environment for PSP's planned trajectory during its mission duration. This empirical model yields estimated solar-wind values for PSP's 1st perihelion in 2018 at 0.16 au: 87 nT, 340 km s-1, 214 cm-3 and 503000 K. The estimates for PSP's first closest perihelion, occurring in 2024 at 0.046 au, are 943 nT, 290 km s-1, 2951 cm-3, and 1930000 K. Since the modeled velocity and temperature values below approximately 20 Rs appear overestimated in comparison with existing observations, this suggests that PSP will directly measure solar-wind acceleration and heating processes below 20 Rs as planned.