论文标题
陆地形成区域中的水紫外线挡层：H2-18O红外发射和陨石中的氧气18同位素异常的影响
Water UV-Shielding in the Terrestrial Planet-Forming Zone: Implications for Oxygen-18 Isotope Anomalies in H2-18O Infrared Emission and Meteorites
论文作者
论文摘要
对原星盘最内向区域中水蒸气的丰度和分布的理解是理解可居住世界和行星系统的起源的关键。过去的观察结果表明，H2O是丰富的，是磁盘表面层中元素氧的主要载体，位于磁盘的内部几个AU内。高丰度和强辐射过渡的组合导致在红外光谱范围内光学厚的发射线。它的稀有同位素H2-18O轨迹更深入到该层，并将追踪行星形成区域的全部内容。在这项工作中，我们探讨了H2-16O和H2-18O在一个模型中的相对分布，该模型包括从紫外线辐射的破坏性效应中进行自屏蔽。在这封信中，我们表明，由于CO，C18O和H2O的自我屏蔽，在0.1-10 au中，相对H2-18O的丰度在温暖的分子层中具有增强。可以用JWST观察的H2-18O的大多数过渡将从该层中部分发射，因此必须考虑H2O自屏障如何影响H2O与H2-18O比率。此外，这种富含H2-18O的气体与垂直“冷手指”效应结合使用的储层可能提供了一种自然机制，可以说明太阳系中的陨石中的氧同位素异常。
An understanding of the abundance and distribution of water vapor in the innermost region of protoplanetary disks is key to understanding the origin of habitable worlds and planetary systems. Past observations have shown H2O to be abundant and a major carrier of elemental oxygen in disk surface layers that lie within the inner few au of the disk. The combination of high abundance and strong radiative transitions leads to emission lines that are optically thick across the infrared spectral range. Its rarer isotopologue H2-18O traces deeper into this layer and will trace the full content of the planet forming zone. In this work, we explore the relative distribution of H2-16O and H2-18O within a model that includes water self-shielding from the destructive effects of ultraviolet radiation. In this Letter we show that there is an enhancement in the relative H2-18O abundance high up in the warm molecular layer within 0.1-10 au due to self-shielding of CO, C18O, and H2O. Most transitions of H2-18O that can be observed with JWST will partially emit from this layer, making it essential to take into account how H2O self-shielding may effect the H2O to H2-18O ratio. Additionally, this reservoir of H2-18O-enriched gas in combination with the vertical "cold finger" effect might provide a natural mechanism to account for oxygen isotopic anomalies found in meteoritic material in the solar system
