论文标题
天王星和海王星的经验结构模型
Empirical Structure Models of Uranus and Neptune
论文作者
论文摘要
天王星和海王星仍然很了解。它们的重力场，旋转期，大气动力学和内部结构尚未得到很好的确定。在本文中，我们介绍了天王星和海王星的经验结构模型，其中密度曲线由多层型表示。通过使用这些模型，设置为适合行星重力场，我们可以预测各种假定旋转期，风深度和低阶谐波的不确定性的高阶重力系数$ J_6 $和$ J_8 $。我们表明，更快的旋转和/或深风有利于集中浓缩的密度分布。我们证明，准确确定$ j_6 $或$ j_8 $，相对不确定性不超过$ 10 \％$可能会限制天王星和海王星的风深度。我们还确认，旅行者的旋转周期与天王星和海王星的测得的形状不一致。接下来，我们证明更准确的重力场可以显着减少内部结构的可能范围。最后，我们建议对天王星和海王星的惯性矩进行准确的测量，其相对不确定性为$ \ sim1 \％$和$ \ sim0.1 \％$，可以分别限制其风的旋转周期和深度。
Uranus and Neptune are still poorly understood. Their gravitational fields, rotation periods, atmosphere dynamics, and internal structures are not well determined. In this paper we present empirical structure models of Uranus and Neptune where the density profiles are represented by polytropes. By using these models, that are set to fit the planetary gravity field, we predict the higher order gravitational coefficients $J_6$ and $J_8$ for various assumed rotation periods, wind depths, and uncertainty of the low-order harmonics. We show that faster rotation and/or deep winds favour centrally concentrated density distributions. We demonstrate that an accurate determination of $J_6$ or $J_8$ with a relative uncertainty no larger than $10\%$ could constrain wind depths of Uranus and Neptune. We also confirm that the Voyager rotation periods are inconsistent with the measured shapes of Uranus and Neptune. We next demonstrate that more accurate determination of the gravity field can significantly reduce the possible range of internal structures. Finally, we suggest that an accurate measurement of the moment of inertia of Uranus and Neptune with a relative uncertainty of $\sim1\%$ and $\sim0.1\%$, could constrain their rotation periods and depths of the winds, respectively.
