Laboratory Measurements of Electrostatic and Magnetostatic Properties of Stellar and Circumstellar Molecules

分子光谱——分子的独特能量特征——携带着关于发现分子的天文环境的物理条件的重要信息。这个研究项目的主要目标是对在恒星黑子和老恒星周围的气体和尘埃中发现的分子的关键特性进行精确的实验室测量。这些性质的准确值将使天文学家能够从这些遥远地区观察到的分子光谱中提取可靠的信息，并推断那里存在的条件。该项目将在先进实验技术方面培养学生和一名博士后研究员。它还将为大学预备学院的高中生和教师提供先进的物理科学体验，并为当地K-12学生提供科学充实。利用最先进的光谱技术，研究小组将精确测量难治性双原子和三原子分子的静电和静磁特性，这些分子是恒星大气和星周包层的已知成分。测量结果将得到(1)Stark光谱中AlO、AlNC、FeNC、SiCN、SiH2、SiN、SiC、HNSi和SiCSi的偶极矩；(2)在与恒星黑子磁场相当的磁场下，光学塞曼测量VO、CrH、FeO、TiH和TiO的磁g因子；VO、AlO、FeO、TiH、CrH和FeH的电子跃迁矩和自发发射率。高质量的实验室数据将允许对大型射电和光学望远镜获得的天文光谱进行最佳利用。关键的天文学应用包括通过精确表征恒星黑子的谱线展宽来消除近红外系外行星搜索中的误报，以及通过射电观测星周包层精确确定分子柱密度。本项目将培养本科生、研究生和一名高级实验室天体物理技术博士后。此外，研究团队将开展活动，吸引亚利桑那州立大学（ASU）预备学院的学生和教师参与物理科学，并将参加亚利桑那州立大学的“科学是有趣的”计划，为K-12学生提供科学丰富，其中许多学生来自科学背景不足。

Molecular spectra---the unique energy signatures of molecules---carry important information about the physical conditions of the astronomical environments in which the molecules are found. The main goal of this research project is to perform accurate laboratory measurements of key properties of molecules that are found in star spots and in the gas and dust around old stars. Accurate values of these properties will allow astronomers to extract reliable information from molecular spectra observed in these distant regions and infer the conditions present there. The project will train students and a postdoctoral researcher in advanced experimental techniques. It will also provide an advanced physical science experience to high school students and teachers at a college preparatory academy and science enrichment to local K-12 students.Using state-of-the-art spectroscopic techniques, the research team will accurately measure the electrostatic and magnetostatic properties of refractory diatomic and triatomic molecules that are known constituents of stellar atmospheres and circumstellar envelopes. The measurements will yield (1) dipole moments of AlO, AlNC, FeNC, SiCN, SiH2, SiN, SiC, HNSi, and SiCSi from optical Stark spectra; (2) magnetic g-factors of VO, CrH, FeO, TiH, and TiO from optical Zeeman measurements under magnetic fields comparable to those in star spots; and (3) electronic transition moments and spontaneous emission rates of VO, AlO, FeO, TiH, CrH, and FeH. The high quality laboratory data will allow optimum exploitation of astronomical spectra obtained with large radio and optical telescopes. Key astronomical applications include the elimination of false positives in exoplanet searches in the near-IR by accurate characterization of spectral line broadening in star spots, and the accurate determination of molecular column densities from radio observations of circumstellar envelopes. This project will train undergraduate and graduate students and a postdoctoral fellow in advanced laboratory astrophysics techniques. Additionally, the research team will conduct activities to engage students and teachers at the Arizona State University (ASU) Preparatory Academy in the physical sciences, and it will participate in ASU's "Science Is Fun" program to provide science enrichment to K-12 students, many of whom come from backgrounds underrepresented in science.