The Curiously Warped Mean Plane of the Kuiper Belt
The Curiously Warped Mean Plane of the Kuiper Belt
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DOI：
10.3847/1538-3881/aa79ff
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发表时间：
2017-08-01
影响因子：
5.3
通讯作者：
Malhotra, Renu
中科院分区：
文献类型：
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作者：
Volk, Kathryn;Malhotra, Renu
我们测量了柯伊伯带的平均平面作为半长轴的函数。对于整个经典柯伊伯带（半长轴范围 42-48 au 内的非共振天体），我们找到平均倾角 i(m) = 1 度.8(-0 度.4)(+0 度.7) 和升交点经度 Omega(m) = 77 度(+18 度)(-14 度)（在 J2000 黄道-分点坐标中）系统），符合已知行星长期影响的理论预期。通过更精细的半长轴箱，我们在半长轴 40-42 au 附近的平均平面中检测到统计上显着的扭曲。线性长期理论预测，由于 nu(18) 节点长期共振，该位置附近会出现扭曲；然而，40.3-42 au 半长轴箱的测量平均平面（就在 nu(18) 之外）与预测平面的倾斜度接近 13 度，接近 3 西格玛的差异。对于半长轴在50-80 au范围内的更遥远的柯伊伯带天体，预期的平均平面接近太阳系不变平面，但测量的平均平面与此相差很大：它的倾角i(m) = 9度.1(-3度.8)(+6度.6)，升交点经度Omega(m) = 277度(+18度)(-44度)。我们估计这种与预期平均平面的偏差在统计上显着，置信水平接近 97%-99%。我们讨论了对这种偏差的几种可能的解释，包括外太阳系中一个相对较近（小于或类似于 100 个天文单位）、看不见的小行星质量物体造成扭曲的可能性。
We measured the mean plane of the Kuiper Belt as a function of semimajor axis. For the classical Kuiper Belt as a whole (the nonresonant objects in the semimajor axis range 42-48 au), we find a mean plane of inclination i(m) = 1 degrees.8(-0 degrees.4)(+0 degrees.7) and longitude of ascending node Omega(m) = 77 degrees(+18 degrees)(-14 degrees) (in the J2000 ecliptic-equinox coordinate system), in accord with theoretical expectations of the secular effects of the known planets. With finer semimajor axis bins, we detect a statistically significant warp in the mean plane near semimajor axes 40-42 au. Linear secular theory predicts a warp near this location due to the nu(18) nodal secular resonance; however, the measured mean plane for the 40.3-42 au semimajor axis bin (just outside the nu(18)) is inclined similar to 13 degrees to the predicted plane, a nearly 3 sigma discrepancy. For the more distant Kuiper Belt objects of semimajor axes in the range 50-80 au, the expected mean plane is close to the invariable plane of the solar system, but the measured mean plane deviates greatly from this: it has inclination i(m) = 9 degrees.1(-3 degrees.8)(+6 degrees.6) and longitude of ascending node Omega(m) = 277 degrees(+18 degrees)(-44 degrees). We estimate this deviation from the expected mean plane to be statistically significant at the similar to 97%-99% confidence level. We discuss several possible explanations for this deviation, including the possibility that a relatively close-in (a less than or similar to 100 au), unseen, small planetary-mass object in the outer solar system is responsible for the warping.