Theoretical Study of the Thermal Histories of Comets and Parent Bodies of Meterorites

对彗星和陨石母体的起源和热历史的研究得出以下结果： 1．建立了彗星核驻留在奥尔特云期间的热历史模型，其中特别考虑了非晶冰极低的热导率。 2．从理论上推导了非晶冰的凝结和保存条件。在此基础上对空间冰的结晶度进行了讨论。 3．通过质子束照射各种成分的模拟宇宙冰，研究了有机材料的形成。 4．导出了颗粒聚集体的拉伸强度，并将结果应用于 Shoemaker-Levy 9.5 彗星的分裂。针对结果1至4，还进行了以下研究：柯伊伯带天体的起源、刚玉颗粒红外吸收系数的测量、星际暗云中H_2O和CO冰的红外天文研究。部分结果已作为系列讲座在1994年6月在埃里塞举办的宇宙尘埃连接国际暑期学校上发表。

The study of the origins and thermal histories of comets and parent bodies of meterorites leads to the following results :1. A new model of the thermal history of cometary nuclei during residence in the Oort cloud has been obtained, in which particular attention has been paid to the extremely low thermal conductivity of amorphous ice is taken into account.2. Conditions for condensation and preservation of amorphous ice have been theoretically derived. Crystallinity of ices in space has been discussed on the basis of the results.3. Formation of organic materials has been studied by irradiating proton beams on simulated cosmic ices of various composition.4. A tensile strength of grain aggregates has been derived, and the results have been applied to the splitting of comet Shoemaker-Levy 9.5. The following study has also been done in relation to the results 1 to 4 : the origin of the Kuiper-belt objects, mesurements of infrared absorption coefficients of corundum grains, and infrared astronomical study of H_2O and CO ices in interstellar dark clouds.Some of the results have been presented as a series of lectures at the International Summer School on Cosmic Dust Connection held at Erice in June 1994.