Astrochemistry: Hydrodynamics, Cosmic ray induced ice chemistry, and Complex Molecules

天体化学是研究宇宙中分子类型及其化学性质的学科。遥远区域的分子本身就很有趣，而且可以作为探测不同区域物理状况的探测器，尤其是被称为致密星际云的区域。恒星和行星在这些充满分子的云中形成，其中一些分子在地球上是相当奇特的。研究人员将研究星际云坍缩和升温过程中发生的化学反应。他们将确定哪些化学反应是最重要的，并模拟这些区域化学成分的变化。星云坍缩的最终产物是低质量恒星，比如太阳，以及比太阳亮得多的高质量恒星。有机（含碳）分子的合成是特别有趣的，因为这些分子可以成为新生行星的一部分，并且通常与生命有关。天体化学的一个关键方面是利用化学模拟再现气体和尘埃颗粒中分子丰度的观测研究，从而了解源寿命和星际和星周介质中的物理条件。化学模拟涉及所谓的耦合动力学微分方程的解，它产生许多分子的列、丰度甚至光谱，作为密度、温度和非均质程度的函数。我们的主要兴趣将是研究恒星的形成。考虑到当前和未来的干涉仪，重点将放在研究发生恒星形成的源的动力学和非均质性上，包括低质量和高质量类别。特别是，三维流体力学将与化学模拟相结合，其初始目标是了解低质量源中的原行星盘、红外黑云、高质量源中的原恒星物体（HMPOs）和热核形成过程中的化学反应。对化学的详细了解应该能提供许多关于恒星形成细节的信息。

Astrochemistry is the study of the types of molecules and their chemistry throughout the universe. Molecules in far-away regions are interesting in themselves and as probes of the physical conditions in various regions, especially regions known as dense interstellar clouds. Stars and planets form in these clouds, which are full of molecules, some quite exotic by terrestrial standards. The investigators will study the chemistry that occurs as interstellar clouds collapse and warm up. They will determine which chemical reactions are most important and simulate the changes in the chemical composition of these regions. The final products of the cloud collapse are low-mass stars, like the sun, as well as high-mass stars, which are far brighter than the sun. The synthesis of organic (carbon-containing) molecules is of special interest, since these molecules can become part of nascent planets and are often associated with life. One critical aspect of astrochemistry is the use of chemical simulations to reproduce observational studies of molecular abundances in the gas and on dust particles, and so learn about source lifetimes and physical conditions in the interstellar and circumstellar media. The chemical simulations involve the solution of so-called coupled kinetic differential equations, which yields columns, abundances, or even spectra of many molecules as functions of density, temperature, and degree of heterogeneity. Our primary interest will be to study star formation. Given current and future interferometers, emphasis will be placed on studying the dynamics and heterogeneity of sources undergoing star formation, both the low-mass and high-mass categories. In particular, three-dimensional hydrodynamics will be combined with chemical simulations with the initial goal of understanding the chemistry that occurs during the formation of protoplanetary disks in low-mass sources, and infrared dark clouds, high-mass protostellar objects (HMPOs), and hot cores in high-mass sources. A detailed understanding of the chemistry should yield much information about the details of star formation.