Collaborative Research: The True Chemical Abundances of Spiral Galaxies

星系究竟是如何形成和发展的，一直是天文学家们所困惑的谜团。 因此，科学家们解开星系形成和发展的线索至关重要。 该项目的重点是螺旋星系中这个谜团的一个非常重要的线索：附近螺旋星系星际介质（ISM）的化学成分（丰度）是如何空间分布的。 研究人员从斯皮策红外邻近星系巡天（SINGS）中仔细选择了一组特定的星系进行这项研究，因为SINGS星系已经拥有出色的多波长观测，可以帮助研究人员解释他们将在该项目中获得的数据。 使用大型双目望远镜（LBT）上的多目标双光谱仪（MODS），研究人员将观察13个SINGS星系的大约1000个电离气体（H II）区域的高质量发射线光谱，将先前观察到的H II区域的数量增加了10倍以上。确保这些新的测量将使研究人员能够解决几个科学问题：（1）ISM化学丰度随半径变化的弥散，（2）旋涡星系化学丰度径向梯度，（3）恒星核合成的元素产额，以及恒星初始质量函数的潜在约束，（4）更远距离星系的化学发展（高红移），和（5）宇宙的化学富集历史。对于这三年中的每一年，该项目将帮助资助一名来自代表性不足群体的研究生（一名女性）的教育，将为一名本科生提供暑期研究职位，并将资助一名博士后科学家。 两位主要调查员还积极参与公共外联活动，以造福于他们的社区。

Exactly how galaxies form and develop is a mystery that has long eluded astronomers. So, it is crucial for scientists to unravel clues of galaxy formation and development. This project focuses on one very important clue to this mystery in spiral galaxies: how the chemical makeup (abundance) of the interstellar medium (ISM) of nearby spiral galaxies is spatially distributed. The investigators have carefully chosen a specific set of galaxies for this study from the Spitzer Infrared Nearby Galaxies Survey (SINGS) because SINGS galaxies have excellent multiwavelength observations already available to aid the investigators in interpreting the data that they will obtain in this project. Using the Multi-Object Double Spectrograph (MODS) on the Large Binocular Telescope (LBT), the investigators will observe high quality emission line spectra of approximately 1000 ionized gas (H II) regions of 13 SINGS galaxies, increasing the number of previously observed H II regions by more than a factor of 10. Securing these new measurements will allow the investigators to address several scientific topics: (1) the dispersion of the ISM chemical abundances as a function of radius, (2) chemical abundance radial gradients in spiral galaxies, (3) the yields of elements from stellar nucleosynthesis with potential constraints on the stellar initial mass function, (4) the chemical development of galaxies at much greater distances (high redshift), and (5) the chemical enrichment history of the Universe.For each of the three years, this project will help fund the education of one graduate student from an underrepresented group (a female), will provide a summer research position for an undergraduate, and will fund a postdoctoral scientist. Both principal investigators are also heavily involved in public outreach activities to benefit their communities.