A Study of Gas Flows and Structure Formation in the Milky Way

地球是由太空中的尘埃气体形成的，围绕着一个年轻的太阳。太阳形成于银河系中一团巨大的分子气体云的核心。研究人员正在研究其他太阳系是如何从高温气体冷却成致密的分子气体云的。研究人员将绘制银河系地图，寻找恒星形成的云层。他们还将研究银河系旋臂的环境。研究人员已经绘制了银河系中许多云的位置。他们的新研究将增加第四个维度，即云速度。这个速度被用来预测云在哪里碰撞形成螺旋臂。这些碰撞会导致新恒星的诞生。研究者将与“信息视觉专家”合作，通过数字外联和直接参与科学和艺术节，将他们的发现带给公众。这些努力将为天文学家提供增强的交互式可视化。气体在一起流动形成气体结构和恒星的过程，在天文学中是一个漫长而难以解决的问题。自从气体旋臂理论开始以来，人们一直在争论旋臂是长寿的星系尺度密度波，还是密度混乱的短暂神话。在所有这些理论中，旋臂的引力势带来了大规模的结合气体流动。这些气流是猛烈的，造成冲击，还是温和的，只是收集气体而不产生冲击，理论不一。目前尚不清楚是通过何种方式（无论是由旋臂驱动还是通过其他方式）组合气流促进了巨分子云（GMC）的形成，也不清楚组合气流对巨分子云的形成是否必要。研究人员希望通过开发和应用一种新技术，动能层析成像（KT）来改变这一领域。KT是一系列方法，将现有的星际介质（ISM）天文测量转化为直接测量气体在哪里聚集形成新结构或在哪里分裂，如距离-速度图所示。这项工作将测试和扩展已经具有功能的原型KT方法，该方法利用了压缩感知等尖端应用数学技术。他们将在大的螺旋臂尺度和较小的GMC尺度上测量ISM的收敛和发散的速率和结构。此外，他们将把这些测量结果与现有的分子云结构数据以及分析理论和模拟的预测结果进行比较。

Earth formed from dusty gas in space, circling a young sun. The sun formed from the core of a huge cloud of molecular gas in our galaxy. The investigators are studying how other solar systems form from hot gas cooling into dense, dark clouds of molecular gas. The investigators will map our galaxy to find clouds where stars are formed. They will also study the environment of our galaxy's spiral arms. The investigators have already mapped many of the positions of the clouds in our galaxy. Their new study will add a fourth dimension, the cloud speed. The speed is used to predict where clouds will collide to form spiral arms. These collisions can result in the birth of new stars.In partnership with expert 'information visualists', the investigator will bring their findings to the public through digital outreach and direct engagement at science and art festivals. These efforts will be attached to enhanced and interactive visualizations for astronomers. The processes by which gas flows together to form gaseous structures and stars is both a long and a difficult problem to solve in astronomy. Since the theory of gaseous spiral arms began, there have been arguments over whether spiral arms are long-lived, galaxy-scale density waves or short-lived myths of density confusions. In all of these theories, the spiral arms' gravitational potential brings large-scale combining gas flows. Theories differ on whether these flows are violent, causing shocks, or gentle, merely collecting gas without shocking it. It is not yet clear by what method of combining flows, whether driven by spiral arms or by other means, encourages the formation of giant molecular clouds (GMCs), or indeed whether combining flows are even necessary for GMC formation.The investigators hope to transform this field by developing and applying a new technique, Kinetic Tomography (KT). KT is a family of methods that transforms already existing astronomical measurements of the interstellar medium (ISM) into a direct measure of where gas is flowing together to form new structures or flowing apart in their destruction, as expressed in the distance-velocity diagram. The proposed work will test and expand the already-functional prototype KT method, which draws on cutting-edge applied math techniques such as compressed sensing. They will measure the rate and structure of convergence and divergence of the ISM, both on the large spiral arm scale and the smaller GMC scale. Furthermore, they will compare these measurements to existing data on molecular cloud structure and predictions from analytic theory and simulations.