Atmospheric Chemistry in Brown Dwarfs and Low Mass Stars

洛德斯博士将在低质量恒星和棕矮星(L和T)的冷大气中研究气体和凝聚化学作为温度、总压和金属丰度的函数。它的动机是需要了解分子气体和云凝聚化学，以便解释对这些天体的光谱观测。第二个主要目标是为这种大气提供可靠的气体、液体和固体化合物网格，这些化合物来自热化学平衡，并在必要时进行热化学动力学计算。这将为冷和低质量恒星的大气和光谱模型提供所需的化学输入。这项工作对于解决低质量天体的关键问题至关重要，包括以下几个问题：L和T矮星的有效温度标度是多少？它们的大气成分是什么？由于垂直输送过程而偏离化学平衡的情况有多常见？云和天气如何影响棕矮星的光谱？洛德斯博士还将把这些结果作为合作工作的一部分，以生成大气模型和低质量天体的高分辨率合成光谱，以确定有效温度、重力和成分随质量和年龄的函数的光谱诊断。该项目是对低质量天体观测研究的补充，并为解释HST、ISO、SIRTF和SOFIA等仪器以及Gemini、Keck、Magellan、2MASS、SDSS和LBT地面观测站未来的观测结果提供了指南。这项工作的结果将通过参考出版物和会议传播，更受欢迎/更有吸引力的结果将通过新闻稿向公众公布。该项目还将有利于现有的与致力于光谱和进化模型的其他研究小组的跨学科合作。本科生(将在这里得到支持)和研究生将通过参与这些项目在这个多学科领域进行培训。

Dr. Lodders will investigate the gas and condensation chemistry as a function of temperature, total pressure, and metallicity in the cool atmospheres of low-mass stars and brown (L and T) dwarfs. It is motivated by the need to understand molecular gas and cloud condensation chemistry in order to interpret the spectroscopic observations of these objects. A second major objective is to provide reliable abundance grids of gaseous, liquid, and solid compounds for such atmospheres derived from thermochemical equilibrium, and where necessary, thermochemical kinetic computations. This will provide the required chemistry inputs for atmospheric and spectral models of cool and low mass stars. The work is essential to address key questions about low-mass objects, including the following: What are the effective temperature scales of L and T dwarfs? What are their atmospheric compositions? How common are departures from chemical equilibrium due to vertical transport processes? How do clouds and weather affect the spectra of brown dwarfs? Dr. Lodders will also apply these results as part of a collaborative work to generate atmospheric models and high-resolution synthetic spectra of low-mass objects to determine spectral diagnostics of effective temperature, gravity, and composition as functions of mass and age. The project is complementary to observational studies of low-mass objects and provides a guide to interpret future observations from instruments such as HST, ISO, SIRTF, and SOFIA and from the ground-based observatories Gemini, Keck, Magellan, 2MASS, SDSS, and the LBT.The results of this work will be disseminated through refereed publications and meetings, with more popular/appealing results being presented to the public through press releases. The project will also benefit the existing interdisciplinary collaboration with other research groups working on spectral and evolutionary models. Undergraduates (to be supported here) and graduate students will be trained in this multidisciplinary field through participation in these projects.