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Gravitational instability and clustering in a disk of planetesimals
stars planetary systems protoplanetary disks – gravitation – planets satellites formation
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2015/12/25
For a long time, gravitational instability in the disk of planetesimals has been suspected to be the main engine responsible for the beginning of dust growth, its advantage being that it provides forr...
Catastrophic disruption of asteroids and family formation:a review of numerical simulations including both fragmentation and gravitational reaccumulations
Asteroids composition Asteroids dynamics Collisional physics Impact processes
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2015/12/25
In the last few years, thanks to the development of sophisticated numerical codes, a major breakthrough has been achieved in our understanding of the processes involved in small bodycollisions. In thi...
Catastrophic disruption of pre-shattered parent bodies
Asteroids composition Asteroids dynamics Collisional physics Impact processes
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2015/12/25
In this paper, we analyze the effect of the internal structure of a parent body on its fragment properties following its disruption in different impact energy regimes. To simulate an asteroid breakup,...
Numerical experiments with rubble piles:equilibrium shapes and spins
Asteroids Planetesimals Rotational dynamics Solid body tides Satellites of Jupiter
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2015/12/25
We present numerical experiments investigating the shape and spin limits of self-gravitating “perfect” rubble piles that consist of identical, smooth, rigid, spherical particles with configurable norm...
The formation of asteroid satellites in large impacts:results from numerical simulations
Asteroids Collisional physics Impact processes Satellites general
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2015/12/25
We present results of 161 numerical simulations of impacts into 100-km diameter asteroids, examining debris trajectories to search for the formation of bound satellite systems. Our simulations utilize...
Numerical simulations of granular dynamics II:Particle dynamics in a shaken granular material
Asteroids, Surfaces Collisional physics Geological processes Regoliths Experimental techniques
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2015/12/25
Surfaces of planets and small bodies of our Solar System are often covered by a layer of granular material that can range from a fine regolith to a gravel-like structure of varying depths. Therefore, ...
Planetesimal clusters in a Keplerian disk I. gravitational evolution
planetary systems formation protoplanetary disks gravitation
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2015/12/25
It was recently demonstrated by numerical simulations that a turbulent flow in a rotating system is capable of efficiently concentrating passively advected particles – having a density larger thanthe ...
N-Body Simulations of Planetesimal Evolution:Effect of Varying Impactor Mass Ratio
planetesimals asteroids planetary formation collisional physics
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2015/12/25
We present results from direct N-body simulations of collisions between gravitational aggregates of varying size as part of a study to parameterize planetesimal growth in the Solar System. We find tha...
Collisions and Gravitational Reaccumulation:Forming Asteroid Families and Satellites
Collisions and Gravitational Asteroid Families Satellites
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2015/12/25
Numerical simulations of the collisional disruption of large asteroids show that although the parent body is totally shattered, subsequent gravitational reaccumulation leads to the formation of an ent...
Direct N-body Simulations of Rubble Pile Collisions
asteroids collisional physics impact processes planetary formation planetesimals
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2015/12/25
There is increasing evidence that many kilometer-sized bodies in the Solar System are piles of rubble bound together by gravity. We present results from a project to map the parameter space of collisi...
Formation of Asteroid Families by Catastrophic Disruption:Simulations with Fragmentation and Gravitational Reaccumulation
asteroids dynamics planetesimals resonances surfaces asteroids
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2015/12/25
This paper builds on preliminary work in which numerical simulations of the collisional disruption of large asteroids (represented by the Eunomia and Koronis family parent bodies) were performed and w...
Direct Large-Scale N-Body Simulations of Planetesimal Dynamics
N-body simulation planetesimals planetary formation planetary dynamics resonances
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2015/12/25
We describe a new direct numerical method for simulating planetesimal dynamics in which N ～ 106 or more bodies can be evolved simultaneously in three spatial dimensions over hundreds ofdynamical times...
1620 GEOGRAPHOS AND 433 EROS:SHAPED BY PLANETARY TIDES?
celestial mechanics stellar dynamics E minor planets asteroids
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2015/12/25
Until recently, most asteroids were thought to be solid bodies whose shapes were determined largely by collisions with other asteroids. Recent work by Burns and others has shown that many asteroids ma...
太阳质子事件中短期预报模型研究
太阳质子事件 太阳质子通量 中短期预报模型 航天任务
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2018/5/4
太阳质子事件通量的预测对航天器抗辐射加固设计和航天员出舱活动具有非常重要的意义.针对一年以下的航天任务，利用经验统计方法，确认太阳活跃年和太阳平静年期间，1——365天不同时间段内 > 10MeV，> 30MeV和 > 60MeV的太阳质子事件积分通量符合对数正态分布，且通量对数的标准偏差σ和期望值μ随任务期时间的变化满足对数函数形式.以此为基础，构建太阳质子通量的中短期预报模型.该模型能够针对太...
A team of Australian researchers used two Maunakea-based observatories – Gemini North and W. M. Keck Observatory – to discover why some galaxies are clumpy rather than spiral in shape and it appears t...