Solving the Puzzle of the Galactic Bar

Gail Zasowski博士被授予NSF天文学和天体物理学博士后奖学金，在俄亥俄州州立大学（OSU）开展研究和教育计划。 我们银河系（MW）最大的未解之谜之一是长中央棒的性质：它的结构，动力学和恒星化学成分。 该酒吧预计将有一个显着的影响，在银河系内部的质量和丰度分布，这是用来表征MW的全球性能和它们与其他星系的关系。 这种特性不仅对理解MW而且对理解一般的星系演化至关重要，因为MW的接近性和可访问性使其成为研究人员开发星系形成和老化模型的最强大资源。 不幸的是，对MW的基本性质的彻底理解一直被排除在外，因为它的内部区域，大部分恒星质量所在的地方，都在中平面的厚厚尘埃后面。 来自多个光度和光谱调查的新红外（IR）数据提供了一种以前所未有的水平探测这些内部区域的方法。 这位研究员计划对内部MW进行全面分析，重点是有影响力但知之甚少的长棒的空间，动力学和化学性质。 该项目将利用前所未有的对内MW中平面的光度和光谱红外观测，包括斯隆数字巡天III的阿帕奇点天文台银河演化实验（APOGEE）提供的独特的高分辨率红外光谱，该研究员将联合收割机结合近红外和中红外光度测量，制作跨越长棒和外凸的恒星的视差校正目录，她将利用这个星表绘制出这些区域的第一张恒星密度图，这张图能够测量长棒的位置、轴比和结构相干性。 她将用APOGEE收集长棒中大量红团（RC）巨星的径向速度，并将其与N体和恒星动力学模型的运动学预测进行比较，以测量棒的系统速度，色散和动力学相干性。 特别感兴趣的是“过渡区”的共振影响酒吧的凸起和酒吧磁盘的关系的运动学。 最后，研究员将使用APOGEE得出的RC样本的金属丰度和丰度来测量金属丰度分布沿着酒吧，包括多个恒星种群的存在。 其结果将是一个完整的图片长酒吧的空间，动力学和化学分布，这可以用来建立酒吧的属性相比，外部星系酒吧，沿着其恒星属性和混合效率。 该研究员将利用俄勒冈州立大学与俄亥俄州的4-H计划的伙伴关系，向儿童和公众证明，科学和科学探究是有趣的，与他们的生活有关，也许最重要的是，所有人都可以访问。 与俄亥俄州4-H州办公室合作，该研究员将通过互动活动为两个教授科学概念的项目做出贡献，重点是那些可以在家里轻松完成的项目。 首先，她将为针对中学生的年度暑期太空营开发以天文学为主题的活动。 其次，她将联合收割机天文学为主题的活动与合适的背景信息和评估指标结合起来，成为4-H项目书系列的空间科学项目书，鼓励学生选择，设计和评估自己的课堂之外的学习经验。 4-H与农村和经济上往往处于不利地位的学校的密切联系意味着，她开发的材料将影响这些服务不足的社区的科学素养。

Dr. Gail Zasowski is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at The Ohio State University (OSU). One of the greatest unresolved puzzles of our Milky Way Galaxy (MW) is the nature of the long central bar: its structure, dynamics, and stellar chemical composition. The bar is expected to have a significant impact on mass and abundance distributions in the inner Galaxy, which are used to characterize the MW's global properties and their relation to those of other galaxies. This characterization is crucial for understanding not only the MW but also general galactic evolution because the proximity and accessibility of the MW makes it the most powerful resource that investigators have to develop models of galaxy formation and aging. Unfortunately, a thorough understanding of the MW's fundamental properties has been precluded as its inner regions, where most of the stellar mass is located, are behind the thick dust of the midplane. New infrared (IR) data from multiple photometric and spectroscopic surveys are providing a way to probe these inner regions at a level never before possible. The fellow plans a comprehensive analysis of the inner MW that focuses on the spatial, dynamical, and chemical properties of the influential but poorly-understood long bar. This project will take advantage of the unprecedented availability of both photometric and spectroscopic infrared observations of the inner MW midplane, including unique high resolution IR spectra from the Sloan Digital Sky Survey III's Apache Point Observatory Galactic Evolution Experiment (APOGEE).The fellow will combine near- and mid-IR photometry to produce an extinction-corrected catalogue of stars spanning the long bar and outer bulge, and she will use this catalogue to make the first stellar density map of these regions that is capable of measuring the long bar's position, axial ratios, and structural coherence. She will collect radial velocities with APOGEE for a large sample of red clump (RC) giants in the long bar and compare them to kinematical predictions from N-body and stellar dynamics models to measure the bar's systematic velocity, dispersion, and dynamical coherence. Of particular interest are the kinematics of the "transition regions" where resonances influence the bar-bulge and bar-disk relationships. Finally, the fellow will use the APOGEE-derived metallicities and abundances of the RC sample to measure the metallicity distribution along the bar, including the presence of multiple stellar populations. The result will be a complete picture of the long bar's spatial, dynamical, and chemical distributions, which can be used to establish the bar's properties compared to external galactic bars, along with its stellar properties and mixing efficiency.The broader impacts of this project include a significant educational component. The fellow will leverage OSU's partnership with Ohio's 4-H program to demonstrate to children and the general public that science and scientific inquiry are fun, relevant to their lives, and perhaps most importantly, accessible to all. In partnership with the Ohio 4-H state office, the fellow will contribute to two projects teaching scientific concepts through interactive activities, with an emphasis on those that can be easily done in the home. First, she will develop astronomy-themed activities for an annual summer Space Camp targeted at middle-school students. Second, she will combine astronomy-themed activities with suitable background information and evaluation metrics into a Space Science Project Book for 4-H's Project Book series, which encourages students to select, design, and evaluate their own learning experiences beyond the classroom. The close association of 4-H with rural and often economically disadvantaged schools means that the materials that she develops will impact the scientific literacy of these underserved communities.