Icy particles from comets
Icy particles from comets
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来自彗星的冰粒子
DOI：
10.1016/0019-1035(89)90137-1
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发表时间：
1989
期刊：
影响因子：
3.2
通讯作者：
R. Giese
中科院分区：
文献类型：
--
作者：
T. Mukai;H. Fechtig;E. Grün;R. Giese
粒子离开彗星的生存概率是根据它们在弹射时刻的轨道变化来检验的。考虑到它们所受的排斥辐射压力加上它们相对于彗核的发射速度，临界半径s1和sc被定义为颗粒半径s <$10 - 5 cm，在这个半径下，具有s1 <$s <$sc的喷射颗粒不能留在太阳系中。我们已经找到了s1和sc的经验公式;例如，对于长周期彗星，半长轴为a Au，近日点距离为q Au，在零发射速度的情况下，sc（cm）= 2.3× 10− 6 a（Au），s1（cm）< 10− 5。被“脏”包裹体污染的半径为s <$100 μm的水冰粒子，被注入到q <$7 Au的束缚轨道，受到行星际尘埃的灾难性碰撞的控制，而那些半径为s <$100 μ m的水冰粒子则受到坡印廷-罗伯逊阻力的控制。与此相反，几乎所有在q = 7 Au轨道上的脏水-冰粒主要由于升华而失去了它们的冰部分。
The survival probability of the particles leaving a comet is examined based on their orbital changes at the moment of ejection. Considering the repulsive radiation pressure on them plus their emission velocities relative to the cometary nucleus, the critical radii s1 and sc are defined in a grain radius s≧ 10− 5 cm, where the ejected grains with s1≦ s≦ sc cannot stay in the Solar System. We have found empirical formulae of s1 and sc; eg, for long-period comets with semimajor axes a≧ 103 AU and perihelion distances q≧ 3 AU, sc (cm)= 2.3× 10− 6 a (AU) and s1 (cm)< 10− 5 in the case of zero emission velocity. Water-ice particles with radii s≧ 100 μm contaminated by “dirty” inclusions, which are injected into bound orbits with q≧ 7 AU, are controlled by catastrophic collisions with interplanetary dust, and those with s≦ 100 μ are controlled by the Poynting-Robertson drag forces. Contrary to that, almost all dirty water-ice grains on orbits with q≦ 7 AU lose their ice parts due mainly to sublimation.