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首页> 外文期刊>Astronomy and astrophysics >Physical properties of the ESA Rosetta target asteroid (21)?Lutetia - II. Shape and flyby geometry
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Physical properties of the ESA Rosetta target asteroid (21)?Lutetia - II. Shape and flyby geometry

机译:ESA Rosetta目标小行星的物理特性(21)?Lutetia-II。形状和飞越几何

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Aims. We determine the physical properties (spin state and shape) of asteroid (21) Lutetia, target of the International Rosetta Mission of the European Space Agency, to help in preparing for observations during the flyby on 2010 July 10 by predicting the orientation of Lutetia as seen from Rosetta. Methods. We use our novel KOALA inversion algorithm to determine the physical properties of asteroids from a combination of optical lightcurves, disk-resolved images, and stellar occultations, although the last are not available for (21) Lutetia. Results. We find the spin axis of (21) Lutetia to lie within 5°?of (λ?=?52°, β?=????6°) in the Ecliptic J2000 reference frame (equatorial α?=?52°, δ?=??+?12°), and determine an improved sidereal period of 8.168270?±?0.000001?h. This pole solution implies that the southern hemisphere of Lutetia will be in “seasonal” shadow at the time of the flyby. The apparent cross-section of Lutetia is triangular when seen “pole-on” and more rectangular “equator-on”. The best-fit model suggests there are several concavities. The largest of these is close to the north pole and may be associated with strong impacts.
机译:目的我们确定小行星(21)Lutetia的物理特性(旋转状态和形状),Lutetia是欧洲航天局国际罗塞塔飞行任务的目标,通过预测Lutetia的方向来帮助为2010年7月10日的掠过期间的观测做准备。从罗塞塔(Rosetta)看到。方法。我们使用新颖的KOALA反演算法从光学曲线,盘分辨图像和恒星掩星的组合中确定小行星的物理属性,尽管最后一种方法不适用于(21)Lutetia。结果。我们发现(21)Lutetia的自旋轴位于黄道J2000参考系(赤道α?=?52°,(λ?=?52°,β?= ???? 6°))的5°?之内。 δθ=Δθ+θ12°),确定改进的恒星周期为8.168270θ±θ0.000001θh。这种极点解决方案意味着路特西亚的南半球在飞越时将处于“季节性”阴影下。当“杆上”看时,Lutetia的视在横截面为三角形,而“赤道上”则看成更矩形。最佳拟合模型表明存在多个凹面。其中最大的是靠近北极,可能与强烈的撞击有关。

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