Population control of Mars Trojans by the Yarkovsky & YORP effects
Population control of Mars Trojans by the Yarkovsky & YORP effects
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DOI：
10.1016/j.icarus.2019.07.004
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发表时间：
2017-10
期刊：
影响因子：
3.2
通讯作者：
A. Christou;G. Borisov;A. Dell’Oro;Seth Andrew Jacobson;A. Cellino;E. Unda-Sanzana
中科院分区：
文献类型：
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作者：
A. Christou;G. Borisov;A. Dell’Oro;Seth Andrew Jacobson;A. Cellino;E. Unda-Sanzana
我们探讨的假设，火星特洛伊人的人口是通过YORP效应和他们最终逃离特洛伊云通过Yarkovsky驱动的轨道演化的新的小行星（“YORPlets”）的生产之间的平衡的结果。我们的主要观测数据是：（5261）尤里卡，它的8个小行星家族和没有家族的特洛伊人（101429）1998 VF 31和（121514）1999 UJ 7。我们将种群演化模型化为一个生灭随机过程，并假设它处于稳态。然后，我们模拟发现的特洛伊木马的日期，并发现家庭成员101429和121514，如果他们存在，本质上更难以检测比尤里卡的。只有在假设它们相对于母小行星的亮度与尤里卡家族的亮度相似的情况下，它们才能被用作不存在的证据。为了找出如何有效地火星特洛伊木马丢失的特洛伊云由于Yarkovsky效应，我们进行动力学模拟的测试粒子来自这些母体。我们发现，来自尤里卡和121514开始逃逸后~1 Gyr，但那些从101429已经失去了那个时候，可能是由于该小行星的接近一个偏心型的长期共振在火星的共轨道区域。这可能是101429轨道附近没有特洛伊人的原因。相比之下，121514的孤立状态表明，在太阳系历史的最近~20%的时间里，小行星本身无法产生YORPlets，这一发现可能与121514目前的低角动量旋转状态有关，除非尤里卡家族在一次裂变事件中迅速形成。
We explore the hypothesis that the population of Martian Trojans is the result of a balance between the production of new asteroids (“YORPlets”) through the YORP effect and their eventual escape from the Trojan clouds through Yarkovsky-driven orbital evolution. Our principal observables are: (5261) Eureka, its family of 8 asteroids and the family-less Trojans (101429) 1998 VF31& (121514) 1999 UJ7. We model the population evolution as a birth-death random process and assume it is in a steady state. We then simulate the discovery of Trojans to-date and find that family members of 101429 and 121514, if they exist, are intrinsically more difficult to detect than Eureka's. Their non-discovery can be used as evidence of their non-existence only under the assumption that their brightness relative to the parent asteroid is similar to that in the Eureka family. To find out how efficiently Mars Trojans are lost from the Trojan clouds due to the Yarkovsky effect, we carry out dynamical simulations of test particles originating from these parent bodies. We find that objects originating from Eureka and 121514 begin escaping after ~1 Gyr, but that those from 101429 are already lost by that time, probably due to that asteroid's proximity to an eccentricity-type secular resonance within Mars's co-orbital region. This is the likely cause behind the absence of Trojans in the orbital vicinity of 101429. In contrast, the solitary status of 121514 points to an intrinsic inability of the asteroid to produce YORPlets during the most recent ~20% of the solar system's history, a finding potentially related to 121514’s present, low angular momentum rotational state, unless the Eureka family formed rapidly during a single fission event.