The CODEX of the Milky Way

恒星是星系的基本组成部分，比如我们的银河系。要了解星系的演化，乃至宇宙的历史，就需要彻底了解不同类型的恒星是如何随时间变化的。恒星都有自己的生命周期，从诞生于冷云中，到成熟为我们在夜晚看到的恒星，再到最后成为红巨星，有时甚至是壮观的超新星。然而，人们对恒星形成的过程仍然知之甚少，这主要是因为很难观察到发生在可见光无法穿透的寒冷、黑暗分子云中的过程。相反，天文学家使用波长较长的辐射，如红外光或无线电波，来发现恒星形成的重要细节，包括形成分子所需的温度、密度和元素的丰度。研究者将以一种引人注目的方式与公众分享他们的研究，通过在学童中开展“科学+艺术”的推广活动，强调科学与艺术之间的重要联系，以供公众欣赏，并增加这项研究的影响。研究者研究的一个主要目标是测试星系中分子发射的模型，该模型基于云层中一氧化碳（CO）分子的毫米波发射图。天文学家之所以对银河系进行CO观测，是因为这种分子分布广泛，相对容易观测。这位研究者最近发表的研究表明，对CO映射的简单解释可能会微妙地误导我们对云中物理条件的理解，云主要由氢分子（H2）组成，很难直接探测到。简而言之，CO映射在追踪H2时可能存在偏差。研究者将完成并向社区发布他们的银河系分子线调查，作为银河系致密气体和激发联合图谱（CODEX）。此外，他们将提供分子云物理条件的更复杂的计算，这是以前从未尝试过的，除非在更小的尺度上。这将使天文学家更好地了解H2分子如何在引力的影响下聚集在一起，在整个银河系中形成恒星，进而在其他螺旋星系中形成恒星。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Stars are the basic building blocks of galaxies like our own Milky Way. Understanding galaxy evolution, and indeed the history of the universe, requires a thorough understanding of how different types of stars change with time. Stars have their own life cycle, from stellar birth in cold clouds, through their maturity as the stars we see at night, to their ends as red giants or sometimes spectacular supernovae. The process of forming stars, however, is still poorly understood, mainly due to the difficulty in observing the processes that take place inside cold, dark molecular clouds which visible light cannot penetrate. Instead, astronomers use longer-wavelength radiation, like infrared light or radio waves, to discover important details of star formation, including the temperature, density and abundances of elements that are needed to form molecules. The investigator will share their research with the public in a striking way, by launching a “science+art” outreach effort to schoolchildren, emphasizing the important connections between science and art for the general public's appreciation, and increasing the impact of this research.A primary goal of the investigator’s research is testing models for molecular emission in the galaxy, based on maps of mm-wave emission from carbon monoxide (CO) molecules in clouds. Astronomers make CO observations of the Milky Way because the molecule is widespread and relatively easy to observe. The investigator has recently published research suggesting simple interpretations of CO mapping may be subtly misleading our understanding of the physical conditions in clouds, which are mostly made up of molecular hydrogen (H2) that is very difficult to detect directly. In short, the CO maps can be biased in tracing H2. The investigator will complete and release to the community their molecular line survey of the Milky Way as the Combined Dense Gas and Excitation Atlas of the Milky Way (the CODEX). In addition, they will provide a more sophisticated calculation of the physical conditions in molecular clouds, something which has not been attempted before excepting on much smaller scales. This will allow astronomers to better understand how the H2 molecules assemble under the influence of gravity to make stars throughout the Milky Way, and by extension, in other spiral galaxies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.