标题： 关于富含冰的天体的结构及其长期演化 显示英文标题

标题： On the structure and long-term evolution of ice-rich bodies

摘要： 人们对富含冰的行星体结构的兴趣，特别是冰与岩石之间的分化，由于柯伊伯带天体和系外行星的发现而增加。 因此，我们针对一系列行星质量（$M$），对应的半径为$50 \aplt R \aplt 3000$公斤，并且对于0.25到4之间的岩石/冰质量比，在寒冷环境中演化4.5千兆年，以获得当前的结构。 我们使用了一个热演化模型，该模型允许在多孔介质中存在液态和气态流动，求解了围绕中心恒星运行的球形天体在流体静力平衡下的质量和能量守恒方程。 该模型包括压力对孔隙度和熔点的影响，由长寿命放射性同位素引起的加热，以及温度依赖的蛇纹石化和脱水作用。 我们在参数空间[大小，岩石含量]中获得了分化形成岩石核心的天体与未分化的天体之间的边界：小天体、低岩石含量的天体以及被认为内部压力最高的最大天体，几乎达到熔化温度。 最终分化的结构包括一个岩石核心、一个富含冰的地幔以及表面下方的一层薄而致密的地壳。 我们得到了并讨论了总体密度-半径关系。 我们研究了非常寒冷环境的影响，发现当环境温度为$\sim$20 K时，小天体将冰保存为非晶态直至现在。 显示英文摘要

摘要： The interest in the structure of ice-rich planetary bodies, in particular the differentiation between ice and rock, has grown due to the discovery of Kuiper belt objects and exoplanets. We thus carry out a parameter study for a range of planetary masses $M$, yielding radii $50 \aplt R \aplt 3000$~km, and for rock/ice mass ratios between 0.25 and 4, evolving them for 4.5~Gyr in a cold environment, to obtain the present structure. We use a thermal evolution model that allows for liquid and vapor flow in a porous medium, solving mass and energy conservation equations under hydrostatic equilibrium for a spherical body in orbit around a central star. The model includes the effect of pressure on porosity and on the melting temperature, heating by long-lived radioactive isotopes, and temperature-dependent serpentinization and dehydration. We obtain the boundary in parameter space [size, rock-content] between bodies that differentiate, forming a rocky core, and those which remain undifferentiated: small bodies, bodies with a low rock content, and the largest bodies considered, which develop high internal pressures and barely attain the melting temperature. The final differentiated structure comprises a rocky core, an ice-rich mantle, and a thin dense crust below the surface. We obtain and discuss the bulk density-radius relationship. The effect of a very cold environment is investigated and we find that at an ambient temperature of $\sim$20~K, small bodies preserve the ice in amorphous form to the present.