The thermal histories and time evolutions of icy planetesimals are numerically solved with various parameters (the time of formation that corresponds to the ratio of 26Al/27Al, the size of the planetesimals and their initial temperature). We consider the formation of a rocky core due to the settling of rocks after the melting of ice. We also take into account two chemical reactions, aqueous alteration and a dehydration reaction, between rocks and water. Results of numerical simulations show that a key factor is the initial ratio of 26Al/27Al. Our results indicate that icy planetesimals, formed at 2.4 Myr after CAI formation, may not reach the melting temperature of ice, regardless of their sizes and initial temperature.
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机译：利用各种参数（包括与 26 Al / 27 Al的比值对应的形成时间）对冰状小行星的热历史和时间演化进行数值求解。行星及其初始温度）。我们考虑到冰融化后由于岩石沉降而形成的岩心。我们还考虑了岩石和水之间的两个化学反应，即水相蚀变和脱水反应。数值模拟结果表明，关键因素是 26 Al / 27 Al的初始比。我们的结果表明，在CAI形成后以2.4 Myr形成的冰小行星可能无法达到冰的融化温度，无论它们的大小和初始温度如何。
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