Collaborative Research:Beyond O/H: Fundamental Astrophysics from HII Region Abundances

星系包含气体和恒星。 气体中的化学物质以发射线的形式留下指纹。 化学丰度可以通过研究发射谱线来测量。 这些研究显示了星系丰度和恒星质量之间的趋势。 它们还显示了星系内部和外部区域之间丰度的趋势。 这些趋势为星系如何形成和演化提供了重要线索。 但是，由于趋势的绝对尺度不确定，线索是混乱的。 为了取得进展，研究小组将用大型双目望远镜在可见光波段观测星系。 他们将使用一种新的NSF仪器来研究星系的发射线。 然后，该小组将分析发射谱线，以确定绝对丰度。 高级团队成员将培训初级团队成员。 该团队将与明尼苏达州的州立公园合作，在新颖的环境中进行公开演讲。 他们还将使用天文馆来接触俄亥俄州低收入地区的K-12学生。该团队将分析13个螺旋星系中HII区域的尖端发射线光谱。 他们的目标是（1）解决基于碰撞激发禁戒线和基于光学复合线的丰度之间数十年的差异，（2）对螺旋星系中的丰度梯度进行明确的研究，（3）设计一种适用于未分辨全局光谱和下一代积分场单位巡天的空间分辨光谱的强线丰度校准。

Galaxies contain gas and stars. The chemicals in the gas leave fingerprints in the form of emission lines. The chemical abundances can be measured by studying the emission lines. These studies show trends between the abundances and the stellar mass of a galaxy. They also show trends in the abundances between the inner and outer regions of a galaxy. Such trends carry important clues about how galaxies form and evolve. But the clues are muddled because the absolute scales for the trends are uncertain. To make progress, the team will observe galaxies at optical wavelengths with the Large Binocular Telescope. They will use a new, NSF-enabled instrument to study the galaxies' emission lines. The team will then analyze the emission lines to determine absolute abundances. Senior team members will train junior team members. The team will partner with the State Parks of Minnesota to give public talks in novel settings. They will also use a planetarium to reach K-12 students in low-income areas of Ohio.The team will analyze cutting-edge emission line spectra of HII regions in 13 spiral galaxies. Their goals are to (1) solve the decades-old discrepancy between abundances based on collisionally-excited forbidden lines and those based on optical recombination lines, (2) conduct a definitive study the abundance gradients in spiral galaxies, and (3) design a calibration of strong-line abundances appropriate to both unresolved global spectra and spatially-resolved spectra from the next generation of surveys with integral field units.