原行星盘暖大气中水的形成
Formation of Water in the Warm Atmospheres of Protoplanetary Disks
摘要：
本文用一个基于X射线加热和电离圆盘大气的模型分析了原行星盘中水的气相化学。几个不确定的过程似乎发挥关键作用，在产生的柱密度的温水，检测磁盘在红外波长。主要因素是形成分子氢的反应，包括在温暖的谷物上形成，以及大气的电离和加热。所有这些都可以共同作用，在内盘大气的分子过渡层中产生一个高水丰度的区域，在那里原子转化为分子，温度从数千开尔文下降到数百开尔文，电离开始由重元素主导。分子氢的颗粒形成和大气的机械加热在这一区域起着重要的作用，并直接影响原行星盘大气中温水的数量。因此，有可能在不引起水从较冷区域向较暖区域的输送的情况下，解释金牛座圆盘中水排放的现有测量结果。羟基自由基OH是下丰富的，在这个模型的磁盘大气，需要考虑额外的生产和激发过程。
英文摘要：
The gas-phase chemistry of water in protoplanetary disks is analyzed with a model based on X-ray heating and ionization of the disk atmosphere. Several uncertain processes appear to play critical roles in generating the column densities of warm water that are detected from disks at infrared wavelengths. The dominant factors are the reactions that form molecular hydrogen, including formation on warm grains, and the ionization and heating of the atmosphere. All of these can work together to produce a region of high water abundances in the molecular transition layer of the inner disk atmosphere, where atoms are transformed into molecules, the temperature drops from thousands to hundreds of Kelvins, and the ionization begins to be dominated by the heavy elements. Grain formation of molecular hydrogen and mechanical heating of the atmosphere can play important roles in this region and directly affect the amount of warm water in protoplanetary disk atmospheres. Thus it may be possible to account for the existing measurements of water emission from Tauri disks without invoking transport of water from cooler to warmer regions. The hydroxyl radical OH is under-abundant in this model of disk atmospheres and requires consideration of additional production and excitation processes.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
