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arXiv 1603.03090astro-ph.EP
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从Herschel和K2观测中发现的海王星外天体(225088)2007 OR10的大尺寸和慢旋转

Large size and slow rotation of the trans-Neptunian object (225088) 2007 OR10 discovered from Herschel and K2 observations

András Pál, Csaba Kiss, Thomas G. Müller, László Molnár, Róbert Szabó, Gyula M. Szab, Krisztián Sárneczky, László L. Kiss

摘要:

我们提出了第一个全面的热和旋转分析的第二个最遥远的trans-Neptunian对象(225088)2007 OR10。我们结合了开普勒空间望远镜-K2扩展任务提供的光学光变曲线和赫歇尔空间天文台提供的热红外数据。我们发现(225088)2007 OR 10可能比早期研究得出的更大更暗:我们得到的直径为d = 1535 ^{+75}_{-225} km,这使得(225088)2007 OR 10成为最大的三个海王星外天体。相应的视觉几何导数为p_V = 0.089 ^{+0.031}_{-0.009}。光变曲线分析显示,该天体的自转速率很慢,为P_rot = 44.81 +/-0.37小时,仅被少数几个天体取代。最有可能的光变曲线解是具有轻微不对称性的双峰,然而,我们不能安全地排除具有对应于单峰解的旋转周期P_rot = 22.40 +/-0.18 h的可能性。由于大小和缓慢的旋转,物体的形状应该是一个麦克劳林椭球,所以光的变化应该是由表面不均匀性引起的。新推导出的较大直径也意味着更大的表面重力和更可能保留挥发分-CH_4,CO和N_2-在表面上。

英文摘要:

We present the first comprehensive thermal and rotational analysis of the second most distant trans-Neptunian object (225088) 2007 OR10. We combined optical light curves provided by the Kepler space telescope -- K2 extended mission and thermal infrared data provided by the Herschel Space Observatory. We found that (225088) 2007 OR10 is likely to be larger and darker than derived by earlier studies: we obtained a diameter of d=1535^{+75}_{-225} km which places (225088) 2007 OR10 in the biggest top three trans-Neptunian objects. The corresponding visual geometric albedo is p_V=0.089^{+0.031}_{-0.009}. The light curve analysis revealed a slow rotation rate of P_rot=44.81+/-0.37 h, superseded by a very few objects only. The most likely light-curve solution is double-peaked with a slight asymmetry, however, we cannot safely rule out the possibility of having a rotation period of P_rot=22.40+/-0.18 h which corresponds to a single-peaked solution. Due to the size and slow rotation, the shape of the object should be a MacLaurin ellipsoid, so the light variation should be caused by surface inhomogeneities. Its newly derived larger diameter also implies larger surface gravity and a more likely retention of volatiles -- CH_4, CO and N_2 -- on the surface.

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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