论文标题
彗星核成分和进化
Comet nuclei composition and evolution
论文作者
论文摘要
多亏了Rosetta Orbiter和Philae Lander的数据，我们对彗星核构图的了解取得了巨大的进步。讨论了67p/cg核的特性，并将其与过去通过空间任务探索的其他彗星进行了比较。彗星核是由冰，矿物质，有机物和盐的集合制成的，导致非常深色和红色的表面。当离太阳很远时，仅在67p/cg的几个位置发现了裸露的水和二氧化碳，其中原始地下层的暴露或由太阳能加热和局部地形形态驱动的挥发物种的再度可以维持其在表面上的临时存在。核表面似乎被厚度可变的灰尘层覆盖。粉尘颗粒大部分出现脱水，是由矿物质，有机物和盐的组合制成的。光谱分析表明，矿物相由硅酸盐，细粒透透和氨盐占主导地位。在有机物中鉴定出具有强羟基的脂肪族和芳香族基团。 The surface composition of cometary nuclei evolves with heliocentric distance and seasonal cycling: approaching perihelion the increase of the solar flux boosts the activity through the sublimation of volatiles which in turn causes the erosion of surface layers, the exposure of ices, the activity in cliffs and pits, the collapse of overhangs and walls, and the mobilization and redistribution of dust.在核的不同形态区域之间发生的颜色，组成和纹理变化的演变与这些过程相关。在本章中，我们讨论了Rosetta Mission在先前由空间任务或从地球观察到的其他彗星的背景下观察到的67p/cg核组成和进化过程。
Thanks to Rosetta orbiter's and Philae lander's data our knowledge of cometary nuclei composition has experienced a great advancement. The properties of 67P/CG nucleus are discussed and compared with other comets explored in the past by space missions. Cometary nuclei are made by a collection of ices, minerals, organic matter, and salts resulting in very dark and red-colored surfaces. When far from the Sun, exposed water and carbon dioxide ices are found only in few locations of 67P/CG where the exposure of pristine subsurface layers or the recondensation of volatile species driven by the solar heating and local terrain morphology can sustain their temporary presence on the surface. The nucleus surface appears covered by a dust layer of variable thickness. Dust grains appear mostly dehydrated and are made by an assemblage of minerals, organic matter, and salts. Spectral analysis shows that the mineral phase is dominated by silicates, fine-grained opaques and ammoniated salts. Aliphatic and aromatic groups, with the presence of the strong hydroxyl group, are identified within the organic matter. The surface composition of cometary nuclei evolves with heliocentric distance and seasonal cycling: approaching perihelion the increase of the solar flux boosts the activity through the sublimation of volatiles which in turn causes the erosion of surface layers, the exposure of ices, the activity in cliffs and pits, the collapse of overhangs and walls, and the mobilization and redistribution of dust. The evolution of color, composition, and texture changes occurring across different morphological regions of the nucleus are correlated with these processes. In this chapter we discuss 67P/CG nucleus composition and evolutionary processes as observed by Rosetta mission in the context of other comets previously explored by space missions or observed from Earth.
