Study of Planetesimals - Origin of Edgeworth - Kuiper belt objects and small bodies in the Solar system

本研究的目的是澄清埃奇沃斯-柯伊伯带天体（eko）和彗星是否是残留的星子。重点是揭示(1)埃奇沃斯-柯伊伯带的结构和(2)太阳系中eko和小天体的物理性质，特别是包括无定形冰在内的挥发性固体的机械强度和性质。(1)评价了埃奇沃斯-柯伊伯带对行星际尘埃供应的贡献。我们发现在埃奇沃斯-柯伊伯带产生了大量的尘埃。讨论了尘埃云的可探测性，以揭示埃奇沃斯-柯伊伯带的整体结构。(2)导出了颗粒材料导热系数的表达式。该结果可应用于冰态行星小体的热史计算，包括其烧结过程中机械强度的演变。揭示了挥发性分子从非晶冰中释放的机理。这项研究的进展导致了对形成太阳系天体的尘埃颗粒形成的研究。揭示了在碳质球粒陨石中发现的太阳前颗粒形成的物理条件。

The goal of the present study is to clarify whether Edgeworth-Kuiper belt objects (EKOs) and comets are remnant planetesimals. Focus is placed on revealing (1) the structure of the Edgeworth-Kuiper belt and (2) physical properties of EKOs and small bodies in the solar system, in particular mechanical strength and properties of volatile solids including amorphous ice.(1) Evaluation is made of the contribution of the Edgeworth-Kuiper belt to supply of interplanetary dust. It is found that substantial amount of dust is produced in the Edgeworth-Kuiper belt. Detectability of the Dust cloud is discussed for revealing the global structure of the Edgeworth-Kuiper belt.(2) An expression of the thermal conductivity of granular materials is derived. The result is applied to the calculations of thermal histories of icy planetenesimals including the evolution of their mechanical strength due to sintering. Release mechanisms of volatile molecules from amorphous ice are also revealed.Progress in the study leads to the study of the formation of dust grains that form solar system bodies. Physical conditions for formation of presolar grains found in the carbonaceous chondrites have been revealed.