论文标题
冰的化学演化，在漂移，形成行星的鹅卵石上
Chemical evolution in ices on drifting, planet-forming pebbles
论文作者
论文摘要
行星及其大气是由原星磁盘中的气体和固体物质建造的。最近的结果表明，诸如鹅卵石之类的固体材料可能会对建立行星氛围产生重大贡献。为了将观察到的系外行星的大气及其组成与它们的形成历史联系起来，重要的是要了解冰卵石在磁盘中径向向内漂移时如何改变其成分。我们的目标是在卵石上漂移圆盘时在卵石上的成分演化建模，并跟踪其化学演化如何在冰块上改变冰的组成相对于从微米大小的晶粒而生长的卵石的冰块组成。最先进的化学动力学代码用于建模化学演化。该代码解释了漂移的固体的随时间不断变化的大小。化学演化是在两个起始半径下为0.1myr的局部建模的，同时将微米大小的固体同时生长成卵石。然后将卵石和局部气体隔离为包裹，然后暴露于变化的物理状况，旨在模仿圆盘中平面中向内漂移的卵石，在三个不同的时间表上移至1 au。一种模型的简化是，鹅卵石是\ emph {not}的移动并暴露于新气体中，但在所有型号中都保持在相同的化学气体周围环境中。对于$> 10^{ - 5} $的冰种，例如h $ _ {2} $ o，co $ _ {2} $，ch $ _ {3} $ oh和nh $ _ {3} $，两种radii and radii of ofient and for tweent and for twe oink and for twe oink and for tw bill drains and drains sill bill drains ships shipss and rad的少于20％，并且较小的时间差不多。对于不太丰富的冰种和最长的漂移时间尺度（1myr），变化较大。卵石漂移化学通常会增加Co $ _ {2} $，HCN的冰丰度，因此，以减少其他挥发性分子的丰富性为代价。
Planets and their atmospheres are built from gas and solid material in protoplanetary disks. Recent results suggest that solid material like pebbles may contribute significantly to building up planetary atmospheres. In order to link observed exoplanet atmospheres and their compositions to their formation histories, it is important to understand how icy pebbles may change their composition when they drift radially inwards in disks. Our goal is to model the compositional evolution of ices on pebbles as they drift in disks, and track how their chemical evolution en-route changes the ice composition relative to the ice composition of the pebbles in the region where they grew from micron-sized grains. A state-of-the-art chemical kinetics code is utilised for modelling chemical evolution. This code accounts for the time-evolving sizes of the solids that drift. Chemical evolution is modelled locally for 0.1Myr at two starting radii, with the micron-sized solids growing into pebbles simultaneously. The pebbles and local gas, isolated as a parcel, is then exposed to changing physical conditions, intended to mimic the pebbles drifting inwards in the disk midplane, moving to 1 AU on three different timescales. A modelling simplification is that the pebbles are \emph{not} moved through, and exposed to new gas, but stay in the same chemical gas surroundings in all models. For ice species with initial abundances relative to hydrogen of $>10^{-5}$, such as H$_{2}$O, CO$_{2}$, CH$_{3}$OH and NH$_{3}$, the abundances change by less than 20% for both radii of origin, and for the two smaller drift timescales (10kyr and 100kyr). For less abundant ice species, and the longest drift timescale (1Myr), the changes are larger. Pebble drift chemistry generally increases the ice abundances of CO$_{2}$, HCN and SO, at the expense of decreasing abundances of other volatile molecules.
