Astrometry and dynamics of Anthe (S/2007 S 4), a new satellite of Saturn
Astrometry and dynamics of Anthe (S/2007 S 4), a new satellite of Saturn
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DOI：
10.1016/j.icarus.2008.01.006
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发表时间：
2008-06
期刊：
影响因子：
3.2
通讯作者：
N. Cooper;C. Murray;M. Evans;K. Beurle;R. Jacobson;C. Porco
中科院分区：
文献类型：
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作者：
N. Cooper;C. Murray;M. Evans;K. Beurle;R. Jacobson;C. Porco
我们描述的天体测量学和动力学的Anthe（S/2007 S 4），一个新的土星卫星发现的图像中获得的使用成像科学子系统（ISS）的卡西尼号飞船。包括63次观测的细节，其中28次是用卡西尼号的窄角相机（NAC）获得的，35次是用它的广角相机（WAC）获得的，覆盖了大约3年的观测时间跨度。我们估计Anthe的直径为1.8公里。基于对观测数据拟合的完整运动方程进行数值积分的轨道建模表明，Anthe与Mimas处于一阶11：10的平均运动共振。有两个共振参数是振动的：λ 1 = 11 λ ′ − 10 λ − λ ′和λ 2 = 11 λ ′ − 10 λ − λ ′ − Ω ′ + Ω，其中λ、λ ′和Ω分别代表土卫一和安西的平均经度、近心经度和升交点经度，其初始量对应于安西。这些共振导致轨道要素的周期性变化。半长轴在913天的周期内变化± 26公里。Anthe也接近于与Methone的77：75形式的二阶偏心型平均运动共振关系。由于Methone也与Mimas处于一阶共振[Spitale，J.N.，雅各布森，R.A.，Porco，C.C.，欧文，W. M.，2006. Astron. J. 132，692 - 710]，一个额外的间接扰动存在于Methone和Anthe之间通过Mimas。在轨道拟合中，这两种效应都无法检测到，并且Anthe的短期动力学演化仅由Mimas-Anthe共振主导。在这段时间内，来自土卫三4：2倾角共振的预期调制效应也是不显著的。通过在数值积分拟合中包括卡西尼国际空间站对土卫一的观测，我们估计土卫一的GM为2.509 ± 0.004 km3s − 2，与Jacobson等人[Jacobson，R.A.，Spitale，J.，波尔科，CC，欧文，W. M.，2006. J. 132，711 - 713]。
We describe the astrometry and dynamics of Anthe (S/2007 S 4), a new satellite of Saturn discovered in images obtained using the Imaging Science Subsystem (ISS) of the Cassini spacecraft. Included are details of 63 observations, of which 28 were obtained with Cassini's narrow-angle camera (NAC) and 35 using its wide-angle camera (WAC), covering an observation time-span of approximately 3 years. We estimate the diameter of Anthe to be ∼1.8 km. Orbit modeling based on a numerical integration of the full equations of motion fitted to the observations show that Anthe is in a first-order 11:10 mean motion resonance with Mimas. Two resonant arguments are librating: ϕ1=11λ′−10λ−ϖ and ϕ2=11λ′−10λ−ϖ′−Ω′+Ω, where λ, ϖ and Ω refer to the mean longitude, longitude of pericenter and longitude of ascending node of Mimas and Anthe, with the primed quantities corresponding to Anthe. These resonances cause periodic variations in the orbital elements. The semi-major axis varies by ±26 km over a 913-day period. Anthe is also close to a second-order eccentricity-type mean motion resonant relationship of the form 77:75 with Methone. Since Methone is also in a first-order resonance with Mimas [Spitale, J.N., Jacobson, R.A., Porco, C.C., Owen, W.M., 2006. Astron. J. 132, 692–710], an additional indirect perturbation exists between Methone and Anthe via Mimas. Neither effect is detectable in the orbit fitting and the short-term dynamical evolution of Anthe is dominated by the Mimas–Anthe resonances alone. The expected modulation effect from the Mimas–Tethys 4:2 inclination resonance is also insignificant over this time period. By including Cassini ISS observations of Mimas in the numerical integration fit, we estimate the GM of Mimas to be 2.509±0.004 km3s−2, consistent with Jacobson et al. [Jacobson, R.A., Spitale, J., Porco, C.C., Owen, W.M., 2006. Astron. J. 132, 711–713].