Collaborative Research: The True Chemical Abundances of Spiral Galaxies

星系究竟是如何形成和发展的，这是一个长期困扰天文学家的谜。因此，对科学家来说，解开星系形成和发展的线索至关重要。这个项目的重点是在螺旋星系中解开这个谜团的一个非常重要的线索：附近螺旋星系的星际介质（ISM）的化学组成（丰度）是如何在空间上分布的。研究人员仔细地从斯皮策红外邻近星系调查（SINGS）中选择了一组特定的星系来进行这项研究，因为SINGS星系已经有了出色的多波长观测数据，可以帮助研究人员解释他们将在这个项目中获得的数据。利用大型双筒望远镜（LBT）上的多目标双光谱仪（MODS），研究人员将观测到13个星系中大约1000个电离气体（H II）区域的高质量发射谱线，将先前观测到的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化学丰度作为半径函数的分散，(2)螺旋星系中的化学丰度径向梯度，(3)恒星核合成中元素的产量与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），以及(5)宇宙的化学富集历史。每三年，该项目将资助一名来自弱势群体的研究生（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。两位主要研究人员还积极参与公共宣传活动，以造福他们的社区。

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.