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arXiv 1104.4004astro-ph.EP
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与木星一级共振的小行星家族

Asteroid families in the first order resonances with Jupiter

Miroslav Brož, David Vokrouhlický

摘要:

与木星处于一阶平均运动共振中的小行星拥有关于确定巨行星最终结构的过程的重要信息。在这里,我们修改了目前的人口对象在J2/1(赫库巴间隙组),J3/2(希尔达组)和J 4/3(图勒组)的共振。发现的多冲小行星的数量是J2/1 274,J3/2 1197,J 4/3 3 3。利用层次聚类技术和颜色识别,我们在J3/2共振中识别了围绕物体(1911)Schubart的碰撞出生的小行星家族。在最大的小行星(153)希尔达周围也有一个较松散的星团。使用N体数值模拟,我们证明了Yarkovsky效应(从小行星表面的红外热辐射)导致系统漂移的偏心率共振小行星,而它们的半长轴几乎是固定的,由于与木星的强耦合。这是一个不同的机制,从主带家庭,其中雅科夫斯基漂移影响基本上是半长轴。我们用离心率演化确定了Schubart族的年龄为(1.7 ± 0.7)Gyr,Hilda族的年龄> 4Gyr。我们还发现,碰撞出生的集群在J2/1共振将有效地动态分散。因此,如果这些天体中的大多数是来自一个年龄超过1 Gyr的事件的碎片,那么这种共振内稳定种群的陡峭尺寸分布就有意义了。最后,我们测试的稳定性共振人口在木星和土星的交叉相互平均运动共振。特别是,我们发现原始的对象在J3/2共振有效地从他们的轨道时,木星和土星越过他们的1:2平均运动共振。

英文摘要:

Asteroids residing in the first-order mean motion resonances with Jupiter hold important information about the processes that set the final architecture of giant planets. Here we revise current populations of objects in the J2/1 (Hecuba-gap group), J3/2 (Hilda group) and J4/3 (Thule group) resonances. The number of multi-opposition asteroids found is 274 for J2/1, 1197 for J3/2 and 3 for J4/3. Using both hierarchical clustering technique and colour identification we characterise a collisionally-born asteroid family around the object (1911) Schubart in the J3/2 resonance. There is also a looser cluster around the largest asteroid (153) Hilda. Using N-body numerical simulations we prove that the Yarkovsky effect (infrared thermal emission from the surface of asteroids) causes a systematic drift in eccentricity for resonant asteroids, while their semimajor axis is almost fixed due to the strong coupling with Jupiter. This is a different mechanism from main belt families, where the Yarkovsky drift affects basically the semimajor axis. We use the eccentricity evolution to determine the following ages: (1.7+-0.7) Gyr for the Schubart family and >~4 Gyr for the Hilda family. We also find that collisionally-born clusters in the J2/1 resonance would efficiently dynamically disperse. The steep size distribution of the stable population inside this resonance could thus make sense if most of these bodies are fragments from an event older than ~1 Gyr. Finally, we test stability of resonant populations during Jupiter's and Saturn's crossing of their mutual mean motion resonances. In particular we find primordial objects in the J3/2 resonance were efficiently removed from their orbits when Jupiter and Saturn crossed their 1:2 mean motion resonance.

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