RUI: High Resolution Infrared Spectroscopic Observations and Characterization of Ammonia in Comets

这项研究的主要目的是测量几颗彗星中氨（NH3）的丰度，并测量其发射的空间分布和其他特征。太阳星云化学模型预测太阳星云中主要的氮气是氮气（N2），而巨行星星云亚星云中主要的氮气是氨（NH3） （Fegley and Prinn, 1989）。N2/NH3和NH3/H20的比值使one能够测试太阳星云模型，并且是诊断彗星冰起源的重要方法（Lunine 1989, Fegley and Prinn 1989, Womack et al. 1992）。长期以来，人们一直认为氨（NH3）是彗星中挥发性氮的重要储存库，但直到最近，它的存在才被直接观察到。红外探测技术的进步，使得通过彗星在3.0微米波长区域的旋转振动跃迁，直接探测彗星中的NH3成为可能。观测将包括在NH3的nu-1振动带的3微米波长区域检测旋转-振动跃迁。该波段内的Q， R-和P-分支的g因子（荧光效率因子）不可用。为了将其光谱线的观测强度与氨的生成速率联系起来，需要知道这些g因子。因此，作为我对NH3相对丰度分析的一部分，我将使用已知的实验室波段强度和适合彗星条件的非lte旋转分布来计算相关的nu-1 g-因子。该项目的重点是观测彗星中的NH3，这项研究的结果将提供有关NH3丰度和发射性质的重要信息。这些结果将用于帮助回答彗星起源的基本问题，研究NH3是否是作为彗星的原始冰存在的母体分子，并通过检查与发射相关的空间特征，确定是否有一些氨是从一个扩展的来源产生的。新泽西州罗文学院的本科生将协助开发数据简化技术并分析数据。

Abstract - Karen Magee-Sauer The prime objective of the research to be carried out is to make measurements of the ammonia (NH3) abundance in several comets and to measure the spatial profile and other characteristics of the emission. Models of solar nebula chemistry predict that the dominant nitrogen gas in the solar nebula was Nitrogen (N2) while the dominant nitrogen gas in the sub-nebulae of the giant planets was ammonia (NH3) (Fegley and Prinn, 1989). The ratios N2/NH3 and NH3/H20 enable on e to test solar nebula models and are important diagnostics of the origins of cometary ices (Lunine 1989, Fegley and Prinn 1989, Womack et al. 1992). Ammonia (NH3) had long been believed to be a significant reservoir for volatile nitrogen in comets, but until recently its presence had not been directly observed. The advancement of infrared detector technology has made it possible to directly detect NH3 in comets via its rotational vibrational transitions in the 3.0 micron wavelength region. The observations will consist of detecting the rotational- vibrational transition in the 3 micron wavelength region of the nu-1 vibrational band of NH3. The g-factors (fluorescence efficiency factors) of the Q, R-, and P- branches within this band are not available. In order to relate the observed intensity of its spectral lines to a production rate of ammonia, these g-factors need to be known. Therefore, as part of my analysis for the relative abundance of NH3, I will calculate the relevant nu-1 g- factors using known laboratory band intensities and non-LTE rotational distributions appropriate for cometary conditions. The focus of this project is on observing the NH3 in comets, and the results of this research will provide important information on the NH3 abundance and nature of the emission. The results will be used to help answer the basic question of the origin of comets, study whether NH3 is a parent molecule present as a natal ice in comets, and by examining the spatial ch aracteristics associated with the emission, and determine whether some ammonia is produced from an extended source. Undergraduate students at Rowan College of New Jersey will assist in developing data reduction techniques and in analyzing the data.