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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >An empirical model of Saturn's bow shock: Cassini observations of shock location and shape
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An empirical model of Saturn's bow shock: Cassini observations of shock location and shape

机译：土星的弓形激波的经验模型:卡西尼观察的冲击位置和形状

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摘要

We present a new empirical model of Saturn's bow shock that utilizes observations from the Cassini spacecraft. Shock crossings are identified in magnetic field and plasma observations made by Cassini between June 2004 and August 2005. The Cassini crossings are then combined with the crossings made during the Saturn flybys of Pioneer 11, Voyager 1, and Voyager 2. Solar wind dynamic pressures for the Cassini crossings are estimated using upstream electron densities determined from Langmuir wave observations made by the Radio and Plasma Wave System. The crossing positions are rotated into aberrated coordinates to correct for the effect of the planet's orbital motion. In the case of Saturn this rotation is by ～1°. To correct for solar wind dynamic pressure variations, the crossing positions are normalized to the average pressure PSW = 0.048 nPa. The model is then obtained by fitting a conic section to the crossings using a nonlinear least squares technique. To validate the assumptions made in constructing the model, we treat the parameters previously assumed to be constants as variables and fit their values using an optimization routine; this leads to a conic section that is within the positional uncertainty of the model. The spacecraft trajectories are considered, and we conclude that they do not significantly bias the model. The new model is compared to the existing models, and the similarities and differences are discussed. We suggest that the new model gives the most accurate empirical representation of the shape and location of Saturn's bow shock.
机译：我们提出一个新的经验模型土星的弓利用来自卡西尼号的观测的冲击宇宙飞船。磁场和等离子体观察卡西尼号2004年6月至2005年8月。卡西尼号交叉结合口岸在土星的飞越先锋11,旅行者1号和旅行者2号。卡西尼号过境点的动态压力估计使用上游电子密度决定从朗缪尔波观测通过收音机和等离子体波系统。位置旋转到异常的坐标纠正效果的行星的轨道运动。～1°. 变化,十字路口位置都是标准化的平均压力PSW = 0.048 nPa。模型拟合得到的圆锥曲线口岸使用非线性最小二乘法技术。构建模型,我们把参数以前认为是常数作为变量并使用一个优化符合他们的价值观例行的;位置不确定性的模型。航天器轨迹被认为是我们认为他们不明显的偏见该模型。现有的模型和相似之处差异进行了讨论。新模型给出最准确的经验的形状和位置的代表土星的弓形激波。

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