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arXiv 0804.4687astro-ph
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经典柯伊伯带的翘曲面

The Warped Plane of the Classical Kuiper Belt

Eugene Chiang, Hyomin Choi

摘要:

通过对40亿年期间的巨行星和测试粒子的轨道进行数值积分,我们跟踪了柯伊伯带中平面位置的演变。经典柯伊伯带与一个以190万年为周期进动的翘曲的板块相一致。柯伊伯带平面现在的位置可以用线性长期摄动理论计算:该平面的局部法线由该理论的强迫倾角矢量给出,该矢量对每个半长轴都是特定的。柯伊伯带平面并不与不变平面重合,但在稳定区中会偏离它几度。例如,在38 AU的半长轴处,当地柯伊伯带平面的倾角为1.9度,升交点的经度为149.9度,参考J2000的平均黄道和春分点。在43天文单位的半长轴上,当地平面的倾角为1.9度,交点经度为78.3度。柯伊伯带平面只有在无限长的半长轴处才与倾角为1.6 °、节经为107.7 °的不变面合并。柯伊伯带天体相对于柯伊伯带平面的倾角几乎保持不变,即使后者偏离线性理论预测的轨道。相对倾角的恒定性反映了自由振动的无阻尼振幅。目前对经典柯伊伯带天体的观测结果与仅由巨行星扭曲的平面一致,但在确认超过3-sigma之前,样本量需要增加几倍。原则上,理论上预期的平面和观测平面之间的差异可以用来推断围绕太阳运行的尚未看到的质量,但执行这样的计划将是具有挑战性的。

英文摘要:

By numerically integrating the orbits of the giant planets and of test particles over a period of four billion years, we follow the evolution of the location of the midplane of the Kuiper belt. The Classical Kuiper belt conforms to a warped sheet that precesses with a 1.9 Myr period. The present-day location of the Kuiper belt plane can be computed using linear secular perturbation theory: the local normal to the plane is given by the theory's forced inclination vector, which is specific to every semimajor axis. The Kuiper belt plane does not coincide with the invariable plane, but deviates from it by up to a few degrees in stable zones. For example, at a semimajor axis of 38 AU, the local Kuiper belt plane has an inclination of 1.9 deg and a longitude of ascending node of 149.9 deg when referred to the mean ecliptic and equinox of J2000. At a semimajor axis of 43 AU, the local plane has an inclination of 1.9 deg and a nodal longitude of 78.3 deg. Only at infinite semimajor axis does the Kuiper belt plane merge with the invariable plane, whose inclination is 1.6 deg and nodal longitude is 107.7 deg. A Kuiper belt object keeps its inclination relative to the Kuiper belt plane nearly constant, even while the latter plane departs from the trajectory predicted by linear theory. The constancy of relative inclination reflects the undamped amplitude of free oscillation. Current observations of Classical Kuiper belt objects are consistent with the plane being warped by the giant planets alone, but the sample size will need to increase by a few times before confirmation exceeds 3-sigma in confidence. In principle, differences between the theoretically expected plane and the observed plane could be used to infer as yet unseen masses orbiting the Sun, but carrying out such a program would be challenging.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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