The chemistry of galaxies

在自下而上的星系形成图中，矮小星系就像雪花，巨型星系就像雪堆。如果想要了解雪是如何形成和扩散的，注意力应该集中在雪花的结构和分布上。如果想要了解雪是如何积累的，重点应该转移到雪堆上。根据这一逻辑，申请人建议在下一个授权期内重点研究形成恒星的矮小星系和巨型螺旋星系的凸起和盘状物。有针对性地研究矮星在近红外中将有助于更深入地了解它们是如何形成的。并改进了一种新的工具来绘制它们在整个宇宙中的排列。对它们在当地的分布和运动的分析将使我们能够描述局部星系表的轮廓，这是一种高度扁平的结构，在其中发现了银河系和所有其他星系，范围达1500万光年，但人们对此知之甚少。通过对螺旋星系的研究，将有可能收集到气体流动如何影响演化。同时，这项工作将导致一种工具，可靠地测量宇宙最远端星系的化学丰度。

In the bottom-up picture of galaxy formation, dwarf galaxies are like snowflakes and giant galaxies are like snowdrifts.  To learn about how the snow forms and disperses, attention should be focussed on the structure and distribution of the snowflakes.  To learn about how snow accumulates, the focus should shift to the snowdrifts.  Guided by this logic, the applicant proposes to focus studies over the next grant period on star-forming dwarf galaxies and the bulges and disks of giant spiral galaxies.   Pointed studies of dwarfs in the near-infrared will lead to a deeper understanding of how they formed, and refinement of a new tool to map their arrangment throughout the universe.  Analyses of their distribution and motions locally will enable characterization of the profile of the Local Sheet of Galaxies, a highly flattened structure within which the Milky Way and all other galaxies out to 15 million light years are found yet about which little is known.  From studies of spirals, it will be possible to glean how flows of gas have affected evolution.  At the same time, the work will lead to a tool to reliably measure the chemical enrichment of galaxies in the farthest reaches of the universe.