How the Milky Way ticks: comprehending complexity in the interstellar medium, from ethereal wisps to dense structures at the onset of star formation

银河系如何运行：理解星际介质的复杂性，从空灵的缕缕到恒星形成开始时的致密结构

• 批准号: 6843-2013
• 负责人: Martin, Peter
• 金额: $ 3.79万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=520967
• 关键词: How; Milky; Way; ticks; comprehending

I want to understand how our Milky Way Galaxy ticks, why, unlike in other galaxies, there is still an interstellar medium (ISM) in which stars are continually forming. This requires a broad program to understand Galactic ecology, the cycling of the ISM from the diffuse atomic phase to dense molecular clouds, the sites of star formation, and back. So complex is the ISM that comprehending the structure and dynamics at the key stages, from ethereal wisps to dense structures at the onset of star formation, requires exploitation and synthesis of all available multiwavelength data. I am working with international teams at a new frontier revolutionizing this field, in the submillimetre with the Herschel and Planck satellites which image thermal emission by small interstellar dust particles tracing the gas. Deciphering the fascinating evolution of dust becomes necessary because dust is implicated in so many key interstellar processes. An exciting new insight from Planck is polarization, probing the important role of the interstellar magnetic field in the life cycle. A key question that will be addressed is the state of the ISM in the hitherto elusive earliest stages of star formation, before substantial accretion and nuclear ignition reveal new stars. The compact structures that we can now detect in the submillimetre are cold condensations, starless cores. How these form and the dependence on environment are still unkown, but progess can be made by relating the onset and efficiency of core formation, and their mass function, to the larger-scale high column density structures like filaments, and tracing the thermal and dynamical state with molecular line probes. At high Galactic latitudes we see the return cycle, the interstellar cirrus, fairly local gas and dust in the disk, as well as intermediate velocity clouds, part of the Galactic fountain, material thrust out of the disk and circulating in the halo. Comprehending the turbulent structure of the cirrus is essential to learning how molecular clouds form, and has another huge impact because cirrus is a polarized foreground that must be removed to reach the cosmological goals of studies of the cosmic microwave and infrared backgrounds.

我想了解我们的银河系是如何运转的，为什么与其他星系不同，仍然有一个星际介质（ISM），恒星在其中不断形成。 这需要一个广泛的计划来了解银河系的生态，ISM从弥漫的原子阶段到密集的分子云，星星形成的地点，然后返回的循环。 ISM是如此复杂，以至于要理解关键阶段的结构和动力学，从星星形成开始时的飘渺到密集结构，需要利用和综合所有可用的多波长数据。 我正在与国际团队合作，在一个新的前沿革命性的这一领域，在亚毫米与赫歇尔和普朗克卫星的图像热辐射的小星际尘埃粒子跟踪气体。 解密尘埃的迷人演变变得很有必要，因为尘埃与许多关键的星际过程有关。 普朗克的一个令人兴奋的新见解是极化，探索星际磁场在生命周期中的重要作用。 一个关键的问题，将被解决的是状态的ISM在迄今为止难以捉摸的最早阶段的星星形成之前，大量的吸积和核点火揭示新的恒星。 我们现在能在亚毫米波段探测到的紧凑结构是冷凝聚，无星核心。 这些如何形成以及对环境的依赖性仍然是未知的，但是可以通过将核心形成的开始和效率以及它们的质量函数与更大尺度的高柱密度结构（如细丝）联系起来，并用分子线探针追踪热状态和动力学状态来实现。 在银河系高纬度地区，我们看到了返回循环，星际卷云，盘中相当局部的气体和尘埃，以及中速云，银河喷泉的一部分，物质从盘中喷出并在晕中循环。 理解卷云的湍流结构对于了解分子云如何形成至关重要，并且具有另一个巨大的影响，因为卷云是一个极化的前景，必须被移除才能实现宇宙微波和红外背景研究的宇宙学目标。