Surface composition and dynamical evolution of two retrograde objects in the outer solar system: 2008 YB3 and 2005 VD
N. Pinilla-Alonso, A. Alvarez-Candal, M. D. Melita, V. Lorenzi, J. Licandro, J. Carvano, D. Lazzaro, G. Carraro, V. Ali-Lagoa, E. Costa, P. H. Hasselmann
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9 pages, 5 figures, Accepted by Astronomy and Astrophysics: 28 November 2012
Most of the objects in the trans-Neptunian belt (TNb) and related populations move in prograde orbits with low eccentricity and inclination. However, the list of icy minor bodies moving in orbits with an inclination above 40 deg. has increased in recent years. The origin of these bodies, and in particular of those objects in retrograde orbits, is not well determined, and different scenarios are considered. In this paper, we present new observational and dynamical data of two objects in retrograde orbits, 2008 YB3 and 2005 VD. We find that the surface of these extreme objects is depleted of ices and does not contain the 'ultra-red' matter typical of some Centaurs. Despite small differences, these objects share common colors and spectral characteristics with the Trojans, comet nuclei, and the group of grey Centaurs. All of these populations are supposed to be covered by a mantle of dust responsible for their reddish- to neutral-color. To investigate if the surface properties and dynamical evolution of these bodies are related, we integrate their orbits for 10^(8) years to the past. We find a remarkable difference in their dynamical evolutions: 2005 VD' s evolution is dominated by a Kozai resonance with planet Jupiter while that of 2008 YB3 is dominated by close encounters with planets Jupiter and Saturn. Our models suggest that the immediate site of provenance of 2005 VD is the in the Oort cloud, whereas for 2008 YB3 it is in the trans-Neptunian region. Additionally, the study of their residence time shows that 2005 VD has spent a larger lapse of time moving in orbits in the region of the giant planets than 2008 YB3. Together with the small differences in color between these two objects, with 2005 VD being more neutral than 2008 YB3, this fact suggests that the surface of 2005 VD has suffered a higher degree of processing, probably related to cometary activity episodes.
对任意倾角的三体问题中的共振捕获进行了数值研究。无质量的粒子被设置为从1：5共振之外与一颗质量为1000的行星漂移，从而遇到行星的不同平均运动共振的网络。随机构造的样本探索0至180度倾角的参数空间，增量为5度，总计近6x10^5个数值模拟。30个共振内部和外部的行星的位置进行监测。我们发现，逆行共振是出乎意料的更有效的捕获比逆行共振，共振顺序不一定是一个很好的指标，在任意倾角的捕获效率。捕获概率显着下降，在中等样本偏心度的初始倾角范围内[10度，110度]。轨道反演是可能的初始圆形轨道与倾角范围[60度，130度]。在1：1共轨共振中的捕获在大的逆行倾角时很可能发生。如果行星的轨道偏心率大于0.1，则通过偏心Kozai-Lidov机制的作用降低捕获概率。捕获的不对称性出现在内部和外部共振之间，因为被捕获的轨道优先被捕获在内部共振中。逆行共振的相对俘获效率表明，逆行轨道上的达摩克洛和半人马座小行星的动力学寿命必须明显大于逆行轨道上的动力学寿命，这意味着最近发现的逆行共振小行星2006 BZ 8，2008 SO 218，2009 QY 6和1999 LE 31（Morais和Nynui，2013，MNRAS 436，L30）可能是在外部巨行星之间徘徊的最古老的小天体之一。
Mapping stable direct and retrograde orbits around the triple system of asteroids (45) Eugenia
人们普遍认为，了解小行星的组成和轨道演变可能有助于我们了解太阳系的形成过程。众所周知，小行星可能对我们的星球构成威胁。这种重要作用使小行星空间飞行任务成为当前天体动力学和天文学研究中的一个非常热门的课题。考虑到对小行星，特别是对多个系统的空间任务越来越感兴趣，我们提出了一项研究，旨在描述三重小行星系统周围的稳定和不稳定区域（45）尤金妮亚。我们的目标是描述该系统的不稳定和稳定区域，并与系统2001 SN 263-ASTER任务的目标进行比较。此外，Prado（2014年）使用了一种新的概念来绘制轨道，考虑到航天器从所有扰动力单独受到的扰动。该方法也适用于（45）Eugenia。我们提出了稳定和不稳定区域的粒子与0和180度之间的相对倾角。我们发现，（45）Eugenia在逆行和逆行情况下都呈现出较大的稳定区域。这主要是因为这个系统的卫星与主星相比很小，而且它们之间的距离也不是很近。我们还提出了这两个三重系统之间的比较，并讨论这些结果如何指导我们在规划未来的任务。
A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration
We report the detection of a double planetary system around the evolved intermediate-mass star HD 47366 from precise radial-velocity measurements at Okayama Astrophysical Observatory, Xinglong Station, and Australian Astronomical Observatory. The star is a K1 giant with a mass of 1.81+-0.13M_sun, a radius of 7.30+-0.33R_sun, and solar metallicity. The planetary system is composed of two giant planets with minimum mass of 1.75^{+0.20}_{-0.17}Mjup and 1.86^{+0.16}_{-0.15}Mjup, orbital period of 363.3^{+2.5}_{-2.4} d and 684.7^{+5.0}_{-4.9} d, and eccentricity of 0.089^{+0.079}_{-0.060} and 0.278…
Composition of Potentially Hazardous Asteroid (214869) 2007 PA8: An H Chondrite from the Outer Asteroid Belt
有潜在危险的小行星是在其接近地球期间进行物理特性鉴定的一个独特机会。这些小行星的距离很近，使它们能够进行采样返回和载人飞行任务，但如果发生碰撞，也可能对地球上的生命构成风险。因此，详细的矿物学分析是规划未来勘探任务和制定适当缓解战略的关键组成部分。在这项研究中，我们提出了近红外光谱（0.7-2.55微米）的PHA（214869）2007 PA 8获得与美国宇航局红外望远镜设施在其接近地球的2012年11月。对这颗小行星的矿物学分析显示，其表面成分与普通的H型陨石一致。特别地，我们发现2007 PA 8的橄榄石和辉石化学分别是Fa 18（Fo 82）和Fs 16。橄榄石-辉石丰度比估计为47%。这一低橄榄石丰度和测量的带参数，接近H4和H5方解石，表明2007年PA 8的母体经历了热变质，然后才被灾难性地破坏。根据组成的亲和力，接近J5：2共振，估计通量的共振对象，我们确定的Koronis家庭是最有可能的源区2007年PA 8。
The New Generation Planetary Population Synthesis (NGPPS). III. Warm super-Earths and cold Jupiters: A weak occurrence correlation, but with a strong architecture-composition link
