2013年至2020年期间观测到的恒星掩星中Chariklo身体和环的精细物理参数
Refined physical parameters for Chariklo's body and rings from stellar occultations observed between 2013 and 2020
摘要：
半人马座（10199）Chariklo拥有第一个围绕一个小物体发现的环系统。它在2013年首次被恒星掩星观测到。通过恒星掩星可以确定大小和形状，精确度可达千米，并获得掩星物体及其附近的特征。利用2017年至2020年期间观测到的恒星掩星，我们的目标是限制Chariklo及其环的物理参数。我们还确定了环的结构，并获得了精确的天体测量位置的Chariklo。我们预测并组织了几次由Chariklo进行的恒星掩星观测活动。从数据集中测量掩星光变曲线，从中获得进入和离开时间，以及环的宽度和不透明度。这些测量，结合以前的工作的结果，使我们能够获得显着的约束Chariklo的形状和环的结构。我们描述了Chariklo环系统（C1 R和C2 R）的特征，并获得了与之前掩星结果一致但更准确的半径和极方向。我们证实了在C1 R内检测到W形结构和径向宽度的明显变化。观测到的宽度范围在4.8和9.1公里之间，平均值为6.5公里。一个双重观察结果（可见光和红色）未显示C1 R不透明度曲线的任何差异，表明环颗粒的尺寸大于几微米。C1 R环的偏心率被发现是小于0.022（3-西格玛），其宽度的变化可能表明偏心率高于0.005。我们适合一个三轴的形状Chariklo的检测超过11掩星，并确定Chariklo是一致的，与一个椭圆体的半轴为143.8，135.2和99.1公里。最终，我们基于盖亚EDR 3提供了七个毫角秒精度水平的天体测量位置，并使用它来改进Chariklo的星历。
英文摘要：
The Centaur (10199) Chariklo has the first rings system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow the determination of sizes and shapes with kilometre accuracy and obtain characteristics of the occulting object and its vicinity. Using stellar occultations observed between 2017 and 2020, we aim at constraining Chariklo's and its rings physical parameters. We also determine the rings' structure, and obtain precise astrometrical positions of Chariklo. We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the data sets, from which ingress and egress times, and rings' width and opacity were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo's shape and rings' structure. We characterise Chariklo's ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirmed the detection of W-shaped structures within C1R and an evident variation of radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating ring particle's size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3-sigma), and its width variations may indicate an eccentricity higher than 0.005. We fit a tri-axial shape to Chariklo's detections over eleven occultations and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8, 135.2 and 99.1 km. Ultimately, we provided seven astrometric positions at a milliarcseconds accuracy level, based on Gaia EDR3, and use it to improve Chariklo's ephemeris.
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